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<?php |
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|
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namespace WordPress\Reprint\Server; |
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|
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require_once __DIR__ . '/utils.php'; |
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require_once __DIR__ . "/class-database-rows-reader.php"; |
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|
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/** |
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* Generates a MySQL dump as a sequence of SQL fragments, one per call to next_sql_fragment(). |
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* |
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* This class exists because shared hosting environments kill long-running PHP processes. |
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* A traditional mysqldump would time out on large databases. Instead, this producer |
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* yields one SQL fragment at a time — a CREATE TABLE, a batched INSERT, or an UPDATE — |
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* and exposes a JSON cursor after each emitted fragment. The caller can serialize that |
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* cursor, end the HTTP request, and resume at the same SQL-fragment boundary in a later |
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* request. The cursor records emitted SQL progress instead of fetched-but-unemitted rows. |
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* |
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* The producer is a finite state machine that walks through tables sequentially: |
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* |
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* INIT → EMIT_HEADER → NEXT_TABLE → CREATE_TABLE → TABLE_HEADER → |
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* START_INSERT ⇄ EMIT_ROW → (EMIT_OVERSIZED_UPDATE) → … → EMIT_FOOTER → FINISHED |
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* |
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* All values are base64-encoded in the SQL output (via FROM_BASE64('...')). This avoids |
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* charset-related corruption: MySQL interprets string literals according to the |
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* connection charset, but base64 is pure ASCII and the decoded bytes are assigned |
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* directly to the column's declared charset. JSON columns are a special case — MySQL |
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* rejects binary charset input for JSON, so those get an extra CONVERT(... USING utf8mb4). |
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* |
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* For keyed rows, eligible large columns can be inserted as empty strings and then |
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* filled via UPDATE ... SET col = CONCAT(col, chunk) statements. |
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* |
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* Known limitations: |
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* |
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* - Rows too large to be SELECTed. If a row is larger than max_allowed_packet or the |
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* PHP memory_limit, it won't be exported. The underlying assumption is that WordPress |
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* wouldn't be able to use that data anyway. If that turns out to be wrong, and there |
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* are plugins that use huge blobs with byte offset queries, we'll need to add measures |
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* to detect those situations and export that data in chunks. |
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* - Tables without a primary key can't use the oversized row handling as there's no |
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* stable row identifier for the UPDATE ... SET col = CONCAT(col, chunk) WHERE ... query. |
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*/ |
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class MySQLDumpProducer |
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{ |
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/** |
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* Maximum decoded SQL body bytes for one multipart part. |
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* |
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* The producer closes a multi-row INSERT at this limit, or splits or |
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* rejects one oversized row fragment. The exporter uses the same limit to |
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* stop grouping fragments before the complete multipart part becomes |
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* oversized, then checks its final byte length before writing it. |
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*/ |
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public const MAX_SQL_PART_BODY_BYTES = 16 * 1024 * 1024; |
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|
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const STATE_INIT = "init"; |
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const STATE_EMIT_HEADER = "emit_header"; |
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const STATE_NEXT_TABLE = "next_table"; |
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const STATE_CREATE_TABLE = "create_table"; |
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const STATE_TABLE_HEADER = "table_header"; |
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const STATE_START_INSERT = "start_insert"; |
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const STATE_EMIT_ROW = "emit_row"; |
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const STATE_EMIT_OVERSIZED_UPDATE = "emit_oversized_update"; |
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const STATE_EMIT_FOOTER = "emit_footer"; |
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const STATE_FINISHED = "finished"; |
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|
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/** @var mixed PDO or a PDO-compatible adapter. */ |
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private $db; |
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|
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/** @var DatabaseRowsReader */ |
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private $row_reader; |
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|
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/** @var string|null */ |
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private $current_sql_fragment = null; |
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|
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/** @var bool */ |
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private $current_fragment_must_be_its_own_part = false; |
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|
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/** @var string */ |
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private $state = self::STATE_INIT; |
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|
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/** @var int */ |
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private $rows_in_batch = 0; |
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|
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/** @var bool */ |
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private $emit_create_table; |
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|
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/** |
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* Derived from MySQL's max_allowed_packet (at 80% to leave headroom for |
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* protocol framing). Rows whose formatted SQL exceeds this limit are split |
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* into an INSERT with empty placeholders followed by UPDATE ... CONCAT() |
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* statements that append the real data in chunks. |
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* |
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* @var int |
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*/ |
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private $max_statement_size; |
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|
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/** |
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* When a row is too large for a single INSERT, its big columns are split |
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* into chunks and queued here. Each entry tracks the column name, its |
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* data type, the current byte offset into the value, and the total byte |
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* length. Character columns also track a character offset because MySQL's |
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* SUBSTRING() counts characters for those types. The actual data is |
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* re-fetched from the database on demand, keeping cursors small (a few |
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* hundred bytes rather than megabytes of raw data). |
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* |
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* @var array Array of {column: string, data_type: string, byte_offset: int, total_length: int, character_offset?: int} |
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*/ |
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private $oversized_queue = []; |
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|
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/** @var array|null */ |
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private $oversized_pk_values = null; |
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|
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/** @var int */ |
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private $current_statement_size = 0; |
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|
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/** |
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* Reader cursor from before a fetched row which must begin the next INSERT. |
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* |
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* The live producer retains that row in memory. A serialized producer |
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* cursor uses this earlier reader position so a new process fetches the |
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* row again instead of skipping it. |
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* |
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* @var array|null |
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*/ |
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private $reader_cursor_before_retained_record = null; |
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|
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/** |
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* @param object $db Database connection — either a real PDO (MySQL) or a |
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* PDO-compatible adapter (SQLite sites). No type hint because the |
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* adapter isn't a PDO subclass and PHP 7.4 lacks union types. |
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*/ |
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public function __construct($db, $options = []) |
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{ |
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$this->db = $db; |
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$this->row_reader = new DatabaseRowsReader($db, $options); |
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$this->emit_create_table = (bool)($options["create_table_query"] ?? true); |
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|
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if (isset($options["max_statement_size"])) { |
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$this->max_statement_size = (int)$options["max_statement_size"]; |
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} else { |
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$this->max_statement_size = $this->detect_max_statement_size(); |
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} |
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|
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if (isset($options["cursor"])) { |
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$this->initialize_from_cursor($options["cursor"]); |
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} |
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} |
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|
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public function get_sql_fragment(): ?string |
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{ |
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return $this->current_sql_fragment; |
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} |
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|
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public function is_finished(): bool |
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{ |
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return self::STATE_FINISHED === $this->state; |
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} |
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|
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/** Returns whether this fragment must be sent in its own multipart part. */ |
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public function current_fragment_must_be_its_own_part(): bool |
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{ |
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return $this->current_fragment_must_be_its_own_part; |
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} |
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|
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/** |
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* Advances the state machine and populates the next SQL fragment. |
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* |
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* Call get_sql_fragment() after this returns true to retrieve the SQL. |
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* Returns false only when the dump is complete (state = FINISHED). |
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*/ |
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public function next_sql_fragment() |
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{ |
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if ($this->is_finished()) { |
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return false; |
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} |
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|
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$this->current_fragment_must_be_its_own_part = false; |
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|
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if (self::STATE_INIT === $this->state) { |
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if (!$this->row_reader->has_initialized_tables()) { |
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$this->row_reader->initialize_tables_to_process(); |
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} |
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$this->state = self::STATE_EMIT_HEADER; |
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} |
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|
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while (true) { |
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switch ($this->state) { |
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case self::STATE_EMIT_HEADER: |
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$this->emit_sql_header(); |
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$this->state = self::STATE_NEXT_TABLE; |
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$this->current_fragment_must_be_its_own_part = true; |
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return true; |
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|
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case self::STATE_NEXT_TABLE: |
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if ($this->move_to_next_table()) { |
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$this->state = $this->emit_create_table |
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? self::STATE_CREATE_TABLE |
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: self::STATE_TABLE_HEADER; |
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} else { |
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$this->state = self::STATE_EMIT_FOOTER; |
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} |
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break; |
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|
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case self::STATE_EMIT_FOOTER: |
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$this->emit_sql_footer(); |
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$this->state = self::STATE_FINISHED; |
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$this->current_fragment_must_be_its_own_part = true; |
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return true; |
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|
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case self::STATE_CREATE_TABLE: |
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$this->emit_create_table_statement(); |
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$this->state = self::STATE_TABLE_HEADER; |
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$this->current_fragment_must_be_its_own_part = true; |
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return true; |
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|
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case self::STATE_TABLE_HEADER: |
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$this->emit_table_header_comment(); |
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$this->state = self::STATE_START_INSERT; |
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return true; |
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|
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case self::STATE_START_INSERT: |
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if ($this->emit_insert_header()) { |
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return true; |
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} |
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// Empty table — emit_insert_header set state to NEXT_TABLE |
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break; |
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|
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case self::STATE_EMIT_ROW: |
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return $this->emit_row(); |
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|
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case self::STATE_EMIT_OVERSIZED_UPDATE: |
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if ($this->emit_oversized_update()) { |
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$this->current_fragment_must_be_its_own_part = true; |
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return true; |
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} |
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break; |
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|
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case self::STATE_FINISHED: |
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return false; |
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} |
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} |
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|
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return false; |
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} |
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/** |
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* Emits "INSERT INTO ... VALUES (first_row)" as a single fragment. |
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* |
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* The first row is always bundled with the INSERT header to prevent |
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* emitting a dangling "INSERT INTO ... VALUES" with no rows — which |
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* would happen if the caller saves the cursor right after the header |
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* and the data changes before the next request. |
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*/ |
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private function emit_insert_header() |
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{ |
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$this->rows_in_batch = 0; |
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if ($this->row_reader->get_current_record() === null) { |
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if (!$this->row_reader->next_record()) { |
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$this->state = self::STATE_NEXT_TABLE; |
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return false; |
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} |
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} |
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|
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$column_list = implode( |
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",", |
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array_map(function ($col) { |
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return $this->row_reader->quote_identifier($col); |
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}, $this->row_reader->get_current_column_names()) |
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); |
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|
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$header = "INSERT INTO " . $this->row_reader->quote_identifier($this->row_reader->get_current_table()) . " ({$column_list}) VALUES\n"; |
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$this->current_statement_size = strlen($header) + strlen($this->on_duplicate_key()) + 1; |
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|
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$current_record_ends_query_batch = $this->row_reader->is_current_record_at_query_batch_boundary(); |
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$first_row_sql = $this->format_row_for_insert( |
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$this->row_reader->get_current_record(), |
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$this->current_statement_size |
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); |
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$this->current_statement_size += strlen($first_row_sql); |
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|
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$this->row_reader->clear_current_record(); |
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$this->reader_cursor_before_retained_record = null; |
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$this->rows_in_batch = 1; |
| 282 |
|
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// Oversized updates require closing this INSERT with a semicolon so the |
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// subsequent UPDATE statements are syntactically separate. |
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$has_oversized = $this->has_pending_oversized_updates(); |
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|
| 287 |
if ( |
| 288 |
$current_record_ends_query_batch || |
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$this->rows_in_batch >= $this->row_reader->get_batch_size() |
| 290 |
) { |
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$this->finish_insert_batch($header . $first_row_sql, $has_oversized); |
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return true; |
| 293 |
} |
| 294 |
|
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if ($has_oversized) { |
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$sql = $header . $first_row_sql . $this->on_duplicate_key() . ';'; |
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$this->current_sql_fragment = $sql; |
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$this->current_statement_size = 0; |
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$this->state = self::STATE_EMIT_OVERSIZED_UPDATE; |
| 300 |
} else { |
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$sql = $header . $first_row_sql; |
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$this->current_sql_fragment = $sql; |
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$this->state = self::STATE_EMIT_ROW; |
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} |
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|
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return true; |
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} |
| 308 |
|
| 309 |
/** Emits one row with a leading comma, or closes the open INSERT when no row remains. */ |
| 310 |
private function emit_row() |
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{ |
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$reader_cursor_before_current_record = $this->row_reader->get_cursor_state(); |
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if (!$this->row_reader->next_record()) { |
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$this->current_sql_fragment = $this->on_duplicate_key() . ';'; |
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$this->current_statement_size = 0; |
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$this->state = self::STATE_NEXT_TABLE; |
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return true; |
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} |
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|
| 320 |
$row_tuple_bytes = $this->estimate_formatted_row_tuple_bytes( |
| 321 |
$this->row_reader->get_current_record() |
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); |
| 323 |
$maximum_insert_statement_bytes = min( |
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$this->max_statement_size, |
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self::MAX_SQL_PART_BODY_BYTES |
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); |
| 327 |
if ( |
| 328 |
$this->current_statement_size + 1 + $row_tuple_bytes > |
| 329 |
$maximum_insert_statement_bytes |
| 330 |
) { |
| 331 |
// This row fits as the first row of another INSERT, but not in the |
| 332 |
// current one. Keep it in memory for the live producer. A resumed |
| 333 |
// producer uses the earlier cursor and fetches it again. |
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$this->reader_cursor_before_retained_record = $reader_cursor_before_current_record; |
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$this->current_sql_fragment = $this->on_duplicate_key() . ';'; |
| 336 |
$this->current_statement_size = 0; |
| 337 |
$this->rows_in_batch = 0; |
| 338 |
$this->state = self::STATE_START_INSERT; |
| 339 |
return true; |
| 340 |
} |
| 341 |
|
| 342 |
$current_record_ends_query_batch = $this->row_reader->is_current_record_at_query_batch_boundary(); |
| 343 |
$row_sql = $this->format_row_for_insert( |
| 344 |
$this->row_reader->get_current_record(), |
| 345 |
strlen($this->on_duplicate_key()) + 1 |
| 346 |
); |
| 347 |
$this->current_statement_size += strlen($row_sql) + 1; |
| 348 |
$this->row_reader->clear_current_record(); |
| 349 |
$this->rows_in_batch++; |
| 350 |
|
| 351 |
$has_oversized = $this->has_pending_oversized_updates(); |
| 352 |
|
| 353 |
if ( |
| 354 |
$current_record_ends_query_batch || |
| 355 |
$this->rows_in_batch >= $this->row_reader->get_batch_size() |
| 356 |
) { |
| 357 |
$this->finish_insert_batch("," . $row_sql, $has_oversized); |
| 358 |
return true; |
| 359 |
} |
| 360 |
|
| 361 |
if ($has_oversized) { |
| 362 |
$this->current_sql_fragment = "," . $row_sql . $this->on_duplicate_key() . ';'; |
| 363 |
$this->current_statement_size = 0; |
| 364 |
$this->state = self::STATE_EMIT_OVERSIZED_UPDATE; |
| 365 |
} else { |
| 366 |
$this->current_sql_fragment = "," . $row_sql; |
| 367 |
} |
| 368 |
|
| 369 |
return true; |
| 370 |
} |
| 371 |
|
| 372 |
/** Finishes an INSERT batch at its bounded row limit. */ |
| 373 |
private function finish_insert_batch($sql, $has_oversized) |
| 374 |
{ |
| 375 |
$this->current_sql_fragment = $sql . $this->on_duplicate_key() . ';'; |
| 376 |
$this->current_statement_size = 0; |
| 377 |
if ($has_oversized) { |
| 378 |
$this->state = self::STATE_EMIT_OVERSIZED_UPDATE; |
| 379 |
} else { |
| 380 |
$this->state = self::STATE_START_INSERT; |
| 381 |
} |
| 382 |
} |
| 383 |
|
| 384 |
/** |
| 385 |
* Returns a no-op update for rows already written by a stopped INSERT. |
| 386 |
* |
| 387 |
* MyISAM can keep a complete prefix of a multi-row INSERT when the query |
| 388 |
* stops. Repeating that INSERT should skip the existing rows and write the |
| 389 |
* missing rows. Assigning any inserted column to itself handles a simple |
| 390 |
* or composite key without hiding invalid values behind INSERT IGNORE. |
| 391 |
* MySQL can also detect an enforced UNIQUE key whose columns are NOT NULL. |
| 392 |
* A nullable UNIQUE key cannot identify an existing row because MySQL |
| 393 |
* permits more than one row whose unique-key value contains NULL. |
| 394 |
*/ |
| 395 |
private function on_duplicate_key() |
| 396 |
{ |
| 397 |
$first_column = $this->row_reader->get_current_column_names()[0]; |
| 398 |
$quoted_column = $this->row_reader->quote_identifier($first_column); |
| 399 |
return "\nON DUPLICATE KEY UPDATE {$quoted_column} = {$quoted_column}"; |
| 400 |
} |
| 401 |
|
| 402 |
/** |
| 403 |
* Emits DROP TABLE IF EXISTS followed by the CREATE TABLE from SHOW CREATE TABLE. |
| 404 |
* Also handles views (SHOW CREATE TABLE returns 'Create View' for those). |
| 405 |
*/ |
| 406 |
private function emit_create_table_statement() |
| 407 |
{ |
| 408 |
$quoted_table = $this->row_reader->quote_identifier($this->row_reader->get_current_table()); |
| 409 |
try { |
| 410 |
$query = "SHOW CREATE TABLE {$quoted_table}"; |
| 411 |
$result = $this->db->query($query); |
| 412 |
$row = $result->fetch(PdoConstants::fetch_assoc()); |
| 413 |
} catch (\Exception $e) { |
| 414 |
throw new \RuntimeException( |
| 415 |
"Failed to get CREATE TABLE for {$quoted_table}: " . $e->getMessage() . " Query: {$query}" |
| 416 |
); |
| 417 |
} |
| 418 |
|
| 419 |
$sql = null; |
| 420 |
if ($row) { |
| 421 |
if (isset($row["Create Table"])) { |
| 422 |
$sql = $row["Create Table"]; |
| 423 |
} elseif (isset($row["Create View"])) { |
| 424 |
$sql = $row["Create View"]; |
| 425 |
} |
| 426 |
} |
| 427 |
|
| 428 |
if ($sql) { |
| 429 |
// Prevent breaking the line by identifiers with a newline byte in them. |
| 430 |
$header = "--\n-- Table structure for table ".str_replace("\n",'\n',$quoted_table)."\n--\n\n"; |
| 431 |
$drop = "DROP TABLE IF EXISTS {$quoted_table};\n"; |
| 432 |
$this->current_sql_fragment = $header . $drop . $sql . ";"; |
| 433 |
} else { |
| 434 |
$keys = $row ? implode(", ", array_keys($row)) : "(no row returned)"; |
| 435 |
throw new \RuntimeException( |
| 436 |
"SHOW CREATE TABLE {$quoted_table} returned no usable SQL. " . |
| 437 |
"Available keys: {$keys}" |
| 438 |
); |
| 439 |
} |
| 440 |
} |
| 441 |
|
| 442 |
/** |
| 443 |
* Emits SET statements that configure constraint checks and set a strict SQL mode. |
| 444 |
* These are restored in emit_sql_footer(). Without disabling FK checks, tables |
| 445 |
* that reference each other would need to be imported in dependency order. |
| 446 |
* Unique checks stay enabled because replayed INSERT statements use unique |
| 447 |
* keys to recognize rows which are already present. |
| 448 |
* |
| 449 |
* The SQL_MODE explicitly omits NO_ZERO_DATE, NO_ZERO_IN_DATE, and NO_ENGINE_SUBSTITUTION. |
| 450 |
* |
| 451 |
* For dates, many WordPress databases contain zero dates like '0000-00-00' |
| 452 |
* or '0000-00-00 00:00:00' (e.g. in wp_posts.post_date for drafts). The |
| 453 |
* source server may have been running without those restrictions, and the |
| 454 |
* dump must be importable regardless of the target server's default sql_mode. |
| 455 |
* |
| 456 |
* From the MySQL 8.0 Reference Manual (§5.1.11 "Server SQL Modes"): |
| 457 |
* |
| 458 |
* NO_ZERO_DATE — [...] The server requires dates to have nonzero month |
| 459 |
* and day values. If NO_ZERO_DATE is enabled and strict mode is enabled, |
| 460 |
* '0000-00-00' is not permitted and inserts produce an error. [...] |
| 461 |
* If NO_ZERO_DATE is disabled, '0000-00-00' is permitted and inserts |
| 462 |
* produce no warning. |
| 463 |
* |
| 464 |
* NO_ZERO_IN_DATE — [...] Affects whether the server permits dates in |
| 465 |
* which the year part is nonzero but the month or day part is 0. |
| 466 |
* [...] If this mode is disabled, dates with zero parts are permitted |
| 467 |
* and inserts produce no warning. |
| 468 |
* |
| 469 |
* By omitting both flags while keeping STRICT_TRANS_TABLES, the dump |
| 470 |
* preserves MySQL's permissive behavior toward zero dates during import. |
| 471 |
* |
| 472 |
* By omitting NO_ENGINE_SUBSTITUTION, we allow imports to succeed under stricter requirements. |
| 473 |
* Example: A MyISAM source table carries ENGINE=MyISAM into the dump, and the target |
| 474 |
* database uses enforce_storage_engine to InnoDB. With NO_ENGINE_SUBSTITUTION, the |
| 475 |
* import would fail because the target engine is not MyISAM and cannot be substituted. |
| 476 |
* |
| 477 |
* @see https://dev.mysql.com/doc/refman/8.0/en/sql-mode.html#sqlmode_no_zero_date |
| 478 |
* @see https://dev.mysql.com/doc/refman/8.0/en/sql-mode.html#sqlmode_no_zero_in_date |
| 479 |
* @see https://mariadb.com/docs/reference/mdb/system-variables/enforce_storage_engine/ |
| 480 |
*/ |
| 481 |
private function emit_sql_header() |
| 482 |
{ |
| 483 |
$this->current_sql_fragment = self::get_session_setup_sql(); |
| 484 |
} |
| 485 |
|
| 486 |
/** Returns the connection settings required before executing dump SQL. */ |
| 487 |
public static function get_session_setup_sql() |
| 488 |
{ |
| 489 |
return "SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=1;\n" . |
| 490 |
"SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0;\n" . |
| 491 |
// @TODO: Restore STRICT_TRANS_TABLES |
| 492 |
"SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='ONLY_FULL_GROUP_BY,ERROR_FOR_DIVISION_BY_ZERO';\n" . |
| 493 |
"SET AUTOCOMMIT=0;\n"; |
| 494 |
} |
| 495 |
|
| 496 |
/** Emits COMMIT and restores the session variables saved in the header. */ |
| 497 |
private function emit_sql_footer() |
| 498 |
{ |
| 499 |
$footer = |
| 500 |
"\nCOMMIT;\n" . |
| 501 |
"SET SQL_MODE=@OLD_SQL_MODE;\n" . |
| 502 |
"SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS;\n" . |
| 503 |
"SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS;\n"; |
| 504 |
$this->current_sql_fragment = $footer; |
| 505 |
} |
| 506 |
|
| 507 |
/** Emits a SQL comment marking the start of data for the current table. */ |
| 508 |
private function emit_table_header_comment() |
| 509 |
{ |
| 510 |
$comment = "\n--\n-- Dumping data for table " . str_replace("\n",'\n',$this->row_reader->quote_identifier($this->row_reader->get_current_table())) . "\n--\n"; |
| 511 |
$this->current_sql_fragment = $comment; |
| 512 |
} |
| 513 |
|
| 514 |
/** Advances to the next table and resets all per-table state. */ |
| 515 |
private function move_to_next_table() |
| 516 |
{ |
| 517 |
$has_table = $this->row_reader->move_to_next_table(); |
| 518 |
if ($has_table) { |
| 519 |
$this->rows_in_batch = 0; |
| 520 |
$this->oversized_queue = []; |
| 521 |
$this->oversized_pk_values = null; |
| 522 |
$this->current_statement_size = 0; |
| 523 |
$this->reader_cursor_before_retained_record = null; |
| 524 |
} |
| 525 |
return $has_table; |
| 526 |
} |
| 527 |
|
| 528 |
/** |
| 529 |
* Returns the producer cursor as a JSON string. |
| 530 |
* |
| 531 |
* The caller can pass this string back as the "cursor" option to a new |
| 532 |
* MySQLDumpProducer to resume at the current SQL-fragment boundary. The |
| 533 |
* JSON is NOT base64-encoded — that's the HTTP layer's concern (export.php). |
| 534 |
* |
| 535 |
* String values in primary key checkpoints are wrapped in |
| 536 |
* {"__binary__": "<base64>"} markers because raw database bytes can't |
| 537 |
* survive JSON encoding. Complete database rows are omitted. During an |
| 538 |
* open INSERT, a fixed-size hash represents the ordered column names, which |
| 539 |
* are reloaded from table metadata on resume. |
| 540 |
*/ |
| 541 |
public function get_reentrancy_cursor() |
| 542 |
{ |
| 543 |
$cursor_data = $this->reader_cursor_before_retained_record ?? |
| 544 |
$this->row_reader->get_cursor_state(); |
| 545 |
unset( |
| 546 |
$cursor_data["current_row"], |
| 547 |
$cursor_data["current_row_ends_query_batch"], |
| 548 |
$cursor_data["current_column_names"] |
| 549 |
); |
| 550 |
$current_column_names_hash = $this->get_current_column_names_hash(); |
| 551 |
if ($current_column_names_hash !== null) { |
| 552 |
$cursor_data["current_column_names_hash"] = $current_column_names_hash; |
| 553 |
} |
| 554 |
$cursor_data["state"] = $this->state; |
| 555 |
$cursor_data["rows_in_batch"] = $this->rows_in_batch; |
| 556 |
/** |
| 557 |
* Tracking for rows that are larger than max_allowed_packet or |
| 558 |
* max_statement_size. |
| 559 |
*/ |
| 560 |
$cursor_data["oversized_queue"] = $this->encode_oversized_queue_for_cursor($this->oversized_queue); |
| 561 |
$cursor_data["current_statement_size"] = $this->current_statement_size; |
| 562 |
|
| 563 |
$json = json_encode($cursor_data); |
| 564 |
if ($json === false) { |
| 565 |
throw new \RuntimeException( |
| 566 |
"Failed to encode reentrancy cursor: " . json_last_error_msg() |
| 567 |
); |
| 568 |
} |
| 569 |
return $json; |
| 570 |
} |
| 571 |
|
| 572 |
/** Base64-encodes all chunk payloads in the oversized queue for JSON safety. */ |
| 573 |
/** |
| 574 |
* The oversized queue entries are already cursor-safe (just column names, |
| 575 |
* data types, and integer offsets), so encoding is a no-op. |
| 576 |
*/ |
| 577 |
private function encode_oversized_queue_for_cursor($queue) |
| 578 |
{ |
| 579 |
return $queue; |
| 580 |
} |
| 581 |
|
| 582 |
/** Reverses encode_oversized_queue_for_cursor(). */ |
| 583 |
private function decode_oversized_queue_from_cursor($queue) |
| 584 |
{ |
| 585 |
if (!is_array($queue)) { |
| 586 |
return []; |
| 587 |
} |
| 588 |
$decoded = []; |
| 589 |
foreach ($queue as $item) { |
| 590 |
if ( |
| 591 |
!is_array($item) || |
| 592 |
!isset($item['column'], $item['data_type'], $item['byte_offset'], $item['total_length']) |
| 593 |
) { |
| 594 |
throw new \InvalidArgumentException( |
| 595 |
"Invalid cursor: oversized_queue item must contain " . |
| 596 |
"'column', 'data_type', 'byte_offset', and 'total_length' keys" |
| 597 |
); |
| 598 |
} |
| 599 |
$decoded_item = [ |
| 600 |
'column' => $item['column'], |
| 601 |
'data_type' => $item['data_type'], |
| 602 |
'byte_offset' => (int) $item['byte_offset'], |
| 603 |
'total_length' => (int) $item['total_length'], |
| 604 |
]; |
| 605 |
if ($this->row_reader->is_character_string_type($item['data_type'])) { |
| 606 |
if (!array_key_exists('character_offset', $item)) { |
| 607 |
if ((int) $item['byte_offset'] !== 0) { |
| 608 |
throw new \InvalidArgumentException( |
| 609 |
"The saved database pull cursor uses an earlier oversized text format. " . |
| 610 |
"Run db-pull --abort and start again." |
| 611 |
); |
| 612 |
} |
| 613 |
$decoded_item['character_offset'] = 0; |
| 614 |
} else { |
| 615 |
$decoded_item['character_offset'] = (int) $item['character_offset']; |
| 616 |
} |
| 617 |
} |
| 618 |
$decoded[] = $decoded_item; |
| 619 |
} |
| 620 |
return $decoded; |
| 621 |
} |
| 622 |
|
| 623 |
/** |
| 624 |
* Restores internal state from a previously-serialized cursor. |
| 625 |
* |
| 626 |
* The row reader reloads column types and ordered names from table metadata. |
| 627 |
* A missing current table resets the producer to STATE_INIT. An active-table |
| 628 |
* cursor must contain the ordered-column hash saved at its fragment boundary. |
| 629 |
*/ |
| 630 |
private function initialize_from_cursor($cursor) |
| 631 |
{ |
| 632 |
$cursor_data = json_decode($cursor, true); |
| 633 |
if ($cursor_data === null && json_last_error() !== JSON_ERROR_NONE) { |
| 634 |
throw new \InvalidArgumentException( |
| 635 |
'Invalid cursor format: cursor must be valid JSON. ' . |
| 636 |
'JSON error: ' . json_last_error_msg() . '. ' . |
| 637 |
'Received: ' . substr($cursor, 0, 100) |
| 638 |
); |
| 639 |
} |
| 640 |
if (is_array($cursor_data)) { |
| 641 |
if (array_key_exists("current_row", $cursor_data)) { |
| 642 |
throw new \InvalidArgumentException( |
| 643 |
"The saved database pull cursor uses an earlier format. " . |
| 644 |
"Run db-pull --abort and start again." |
| 645 |
); |
| 646 |
} |
| 647 |
|
| 648 |
$this->state = $cursor_data["state"] ?? self::STATE_INIT; |
| 649 |
$this->rows_in_batch = $cursor_data["rows_in_batch"] ?? 0; |
| 650 |
if (!is_int($this->rows_in_batch) && !is_float($this->rows_in_batch)) { |
| 651 |
throw new \InvalidArgumentException( |
| 652 |
"Invalid cursor: rows_in_batch must be numeric, got " . gettype($this->rows_in_batch) |
| 653 |
); |
| 654 |
} |
| 655 |
$this->rows_in_batch = (int) $this->rows_in_batch; |
| 656 |
|
| 657 |
$encoded_queue = $cursor_data["oversized_queue"] ?? []; |
| 658 |
$this->oversized_queue = $this->decode_oversized_queue_from_cursor($encoded_queue); |
| 659 |
$this->oversized_pk_values = null; |
| 660 |
if ($this->state === self::STATE_EMIT_OVERSIZED_UPDATE) { |
| 661 |
// The last emitted primary key identifies the row whose |
| 662 |
// oversized columns are still being appended. |
| 663 |
$this->oversized_pk_values = $this->row_reader->decode_database_values_from_cursor( |
| 664 |
$cursor_data["last_pk_values"] ?? null |
| 665 |
); |
| 666 |
} |
| 667 |
$this->current_statement_size = $cursor_data["current_statement_size"] ?? 0; |
| 668 |
|
| 669 |
if (!$this->row_reader->restore_cursor_state($cursor_data)) { |
| 670 |
$this->state = self::STATE_INIT; |
| 671 |
} else { |
| 672 |
$expected_column_names_hash = $cursor_data["current_column_names_hash"] ?? null; |
| 673 |
$actual_column_names_hash = $this->get_current_column_names_hash(); |
| 674 |
if ($actual_column_names_hash !== null) { |
| 675 |
if ($expected_column_names_hash === null) { |
| 676 |
throw new \InvalidArgumentException( |
| 677 |
"Invalid cursor: an active table cursor must contain current_column_names_hash. " . |
| 678 |
"Run db-pull --abort and start again." |
| 679 |
); |
| 680 |
} |
| 681 |
if ( |
| 682 |
!is_string($expected_column_names_hash) || |
| 683 |
!preg_match('/^[0-9a-f]{64}$/D', $expected_column_names_hash) |
| 684 |
) { |
| 685 |
throw new \InvalidArgumentException( |
| 686 |
"Invalid cursor: current_column_names_hash must be a lowercase SHA-256 string" |
| 687 |
); |
| 688 |
} |
| 689 |
if (!hash_equals($expected_column_names_hash, $actual_column_names_hash)) { |
| 690 |
// phpcs:disable WordPress.Security.EscapeOutput.ExceptionNotEscaped -- Cursor errors are returned as plain API messages. |
| 691 |
throw new \RuntimeException( |
| 692 |
"Cannot restore the database row cursor because the ordered columns for table " . |
| 693 |
$this->row_reader->quote_identifier($this->row_reader->get_current_table()) . |
| 694 |
" changed. Run db-pull --abort and start again." |
| 695 |
); |
| 696 |
// phpcs:enable WordPress.Security.EscapeOutput.ExceptionNotEscaped |
| 697 |
} |
| 698 |
} |
| 699 |
} |
| 700 |
} |
| 701 |
} |
| 702 |
|
| 703 |
/** Returns a fixed-size SHA-256 hash of the current table's ordered column names. */ |
| 704 |
private function get_current_column_names_hash() |
| 705 |
{ |
| 706 |
if ( |
| 707 |
$this->state === self::STATE_NEXT_TABLE || |
| 708 |
$this->row_reader->get_current_table() === null |
| 709 |
) { |
| 710 |
return null; |
| 711 |
} |
| 712 |
$column_names = $this->row_reader->get_current_column_names(); |
| 713 |
if ($column_names === null) { |
| 714 |
return null; |
| 715 |
} |
| 716 |
return hash("sha256", serialize(array_values($column_names))); |
| 717 |
} |
| 718 |
|
| 719 |
/** |
| 720 |
* Formats a single column value as a SQL literal. |
| 721 |
* |
| 722 |
* Numeric types are emitted as bare literals. Everything else — strings, |
| 723 |
* binary, dates, enums — goes through FROM_BASE64(). JSON is special: |
| 724 |
* MySQL rejects binary-charset input for JSON columns, so we wrap with |
| 725 |
* CONVERT(... USING utf8mb4) to decode the base64 into a utf8mb4 string. |
| 726 |
* JSON can only be encoded as UTF-8 or UTF-16, and it's typically UTF-8. |
| 727 |
* As of this version, we do not support UTF-16-encoded JSON data strings. |
| 728 |
* |
| 729 |
* @TODO: Support UTF-16-encoded JSON data strings. |
| 730 |
*/ |
| 731 |
private function format_value($value, $data_type) |
| 732 |
{ |
| 733 |
if ($value === null) { |
| 734 |
return "NULL"; |
| 735 |
} |
| 736 |
|
| 737 |
if ($this->row_reader->is_numeric_type($data_type)) { |
| 738 |
return (string) $value; |
| 739 |
} |
| 740 |
|
| 741 |
if (strtoupper($data_type) === "JSON") { |
| 742 |
if ($value === "") { |
| 743 |
return "''"; |
| 744 |
} |
| 745 |
$base64 = base64_encode($value); |
| 746 |
return "CONVERT(FROM_BASE64('" . $base64 . "') USING utf8mb4)"; |
| 747 |
} |
| 748 |
|
| 749 |
// Treat all other data types as strings and encode them as base64. This |
| 750 |
// allows us to express all possible text encodings and arbitrary binary values. |
| 751 |
if ($value === "") { |
| 752 |
return "''"; |
| 753 |
} |
| 754 |
return "FROM_BASE64('" . base64_encode($value) . "')"; |
| 755 |
} |
| 756 |
|
| 757 |
/** |
| 758 |
* Estimates the byte length of format_value()'s output without actually |
| 759 |
* encoding. Used by format_row_for_insert() to decide whether a row |
| 760 |
* would exceed max_statement_size before doing the expensive encoding. |
| 761 |
*/ |
| 762 |
private function estimate_formatted_size($value, $data_type) |
| 763 |
{ |
| 764 |
if ($value === null) { |
| 765 |
return 4; // NULL |
| 766 |
} |
| 767 |
|
| 768 |
if ($this->row_reader->is_numeric_type($data_type)) { |
| 769 |
return strlen((string) $value); |
| 770 |
} |
| 771 |
|
| 772 |
$len = strlen((string) $value); |
| 773 |
if ($len === 0) { |
| 774 |
return 2; // '' |
| 775 |
} |
| 776 |
|
| 777 |
/** Base64 output is always ceil(n/3)*4 bytes. */ |
| 778 |
$estimated_base64_length = 4 * integer_divide($len + 2, 3); |
| 779 |
// FROM_BASE64('<data>') adds 15 bytes. JSON adds the surrounding |
| 780 |
// CONVERT(... USING utf8mb4), for 38 wrapper bytes in total. |
| 781 |
$wrapper_bytes = strtoupper($data_type) === "JSON" ? 38 : 15; |
| 782 |
return $wrapper_bytes + $estimated_base64_length; |
| 783 |
} |
| 784 |
|
| 785 |
/** Auto-detects max_allowed_packet and uses 80% of it. Falls back to 1MB. */ |
| 786 |
private function detect_max_statement_size() |
| 787 |
{ |
| 788 |
try { |
| 789 |
$result = $this->db->query("SELECT @@max_allowed_packet as max_allowed_packet"); |
| 790 |
$row = $result->fetch(PdoConstants::fetch_assoc()); |
| 791 |
if ($row && isset($row['max_allowed_packet'])) { |
| 792 |
return (int)($row['max_allowed_packet'] * 0.8); |
| 793 |
} |
| 794 |
} catch (\Exception $e) { |
| 795 |
} |
| 796 |
|
| 797 |
return 1024 * 1024; |
| 798 |
} |
| 799 |
|
| 800 |
/** |
| 801 |
* Formats a row as a VALUES tuple, splitting oversized columns if needed. |
| 802 |
* |
| 803 |
* The approach is estimate-first: compute the approximate encoded size of |
| 804 |
* each column before doing the actual (expensive) base64 encoding. If the |
| 805 |
* row fits the statement and part-body limits, encode everything. If it |
| 806 |
* doesn't, replace eligible large non-PK columns with '' and queue their |
| 807 |
* real values as UPDATE ... CONCAT() chunks in $this->oversized_queue. |
| 808 |
* |
| 809 |
* Tables without a primary key can't use the UPDATE fallback because |
| 810 |
* there is no stable row identifier for the WHERE clause. Reject those |
| 811 |
* rows before building an over-limit SQL fragment. |
| 812 |
*/ |
| 813 |
private function format_row_for_insert($row, $sql_fragment_fixed_bytes) |
| 814 |
{ |
| 815 |
$estimated_sizes = []; |
| 816 |
$raw_values = []; |
| 817 |
|
| 818 |
foreach ($this->row_reader->get_current_column_names() as $col) { |
| 819 |
$value = $row[$col] ?? null; |
| 820 |
$raw_values[$col] = $value; |
| 821 |
$data_type = $this->row_reader->get_data_type($col); |
| 822 |
$estimated_sizes[$col] = $this->estimate_formatted_size($value, $data_type); |
| 823 |
} |
| 824 |
|
| 825 |
$row_tuple_bytes = $this->estimate_formatted_row_tuple_bytes($row); |
| 826 |
$row_separator_bytes = $this->rows_in_batch > 0 ? 1 : 0; |
| 827 |
$maximum_insert_statement_bytes = min( |
| 828 |
$this->max_statement_size, |
| 829 |
self::MAX_SQL_PART_BODY_BYTES |
| 830 |
); |
| 831 |
$projected_statement_size = |
| 832 |
$this->current_statement_size + $row_separator_bytes + $row_tuple_bytes; |
| 833 |
$projected_fragment_size = |
| 834 |
$sql_fragment_fixed_bytes + $row_separator_bytes + $row_tuple_bytes; |
| 835 |
|
| 836 |
if ( |
| 837 |
$projected_statement_size <= $maximum_insert_statement_bytes && |
| 838 |
$projected_fragment_size <= self::MAX_SQL_PART_BODY_BYTES |
| 839 |
) { |
| 840 |
$formatted_values = []; |
| 841 |
foreach ($this->row_reader->get_current_column_names() as $col) { |
| 842 |
$data_type = $this->row_reader->get_data_type($col); |
| 843 |
$formatted_values[$col] = $this->format_value($raw_values[$col], $data_type); |
| 844 |
} |
| 845 |
return "(" . implode(",", array_values($formatted_values)) . ")"; |
| 846 |
} |
| 847 |
|
| 848 |
// The rest of this method deals with rows that are too large to fit into a single INSERT on |
| 849 |
// the receiving end. |
| 850 |
|
| 851 |
if (!$this->row_reader->get_current_primary_key_columns() || count($this->row_reader->get_current_primary_key_columns()) === 0) { |
| 852 |
// phpcs:disable WordPress.Security.EscapeOutput.ExceptionNotEscaped -- Protocol error returned as authenticated API data, never HTML. |
| 853 |
throw new \RuntimeException( |
| 854 |
"Row in table " . $this->row_reader->quote_identifier($this->row_reader->get_current_table()) . |
| 855 |
" has an estimated current INSERT size of {$projected_statement_size} bytes and SQL fragment size of" . |
| 856 |
" {$projected_fragment_size} bytes. The limits are max_statement_size" . |
| 857 |
" ({$this->max_statement_size} bytes) and the SQL part body limit" . |
| 858 |
" (" . self::MAX_SQL_PART_BODY_BYTES . " bytes)," . |
| 859 |
" but the table has no primary key, so the oversized row" . |
| 860 |
" cannot be split into UPDATE ... CONCAT() chunks." |
| 861 |
); |
| 862 |
// phpcs:enable WordPress.Security.EscapeOutput.ExceptionNotEscaped |
| 863 |
} |
| 864 |
|
| 865 |
$this->oversized_pk_values = []; |
| 866 |
foreach ($this->row_reader->get_current_primary_key_columns() as $pk_col) { |
| 867 |
if (!array_key_exists($pk_col, $row)) { |
| 868 |
throw new \RuntimeException( |
| 869 |
"Primary key column '{$pk_col}' missing from row for table " . |
| 870 |
$this->row_reader->quote_identifier($this->row_reader->get_current_table()) |
| 871 |
); |
| 872 |
} |
| 873 |
$this->oversized_pk_values[$pk_col] = $row[$pk_col]; |
| 874 |
} |
| 875 |
|
| 876 |
// Split the largest columns first to bring the row under the limit |
| 877 |
$sorted_sizes = $estimated_sizes; |
| 878 |
arsort($sorted_sizes); |
| 879 |
|
| 880 |
$this->oversized_queue = []; |
| 881 |
$chunked_columns = []; |
| 882 |
|
| 883 |
$excess = max( |
| 884 |
$projected_statement_size - $maximum_insert_statement_bytes, |
| 885 |
$projected_fragment_size - self::MAX_SQL_PART_BODY_BYTES |
| 886 |
); |
| 887 |
$saved_bytes = 0; |
| 888 |
$unchunkable_data_types = []; |
| 889 |
|
| 890 |
foreach ($sorted_sizes as $col => $size) { |
| 891 |
if (in_array($col, $this->row_reader->get_current_primary_key_columns())) { |
| 892 |
continue; |
| 893 |
} |
| 894 |
|
| 895 |
if ($size < 1000) { |
| 896 |
continue; |
| 897 |
} |
| 898 |
|
| 899 |
if ($excess <= 0) { |
| 900 |
break; |
| 901 |
} |
| 902 |
|
| 903 |
$raw_value = $raw_values[$col]; |
| 904 |
if ($raw_value === null || $raw_value === '') { |
| 905 |
continue; |
| 906 |
} |
| 907 |
|
| 908 |
$data_type = $this->row_reader->get_data_type($col); |
| 909 |
$normalized_data_type = strtoupper($data_type); |
| 910 |
if ( |
| 911 |
!$this->row_reader->is_binary_type($normalized_data_type) && |
| 912 |
!$this->row_reader->is_character_string_type($normalized_data_type) |
| 913 |
) { |
| 914 |
$unchunkable_data_types[$normalized_data_type] = true; |
| 915 |
continue; |
| 916 |
} |
| 917 |
$value_length = strlen($raw_value); |
| 918 |
$chunk_size = $this->compute_chunk_size($col); |
| 919 |
|
| 920 |
if ($value_length > $chunk_size) { |
| 921 |
$chunked_columns[$col] = true; |
| 922 |
$saved_bytes += $size - 2; // Saved bytes (size minus the '' replacement) |
| 923 |
$excess -= $size - 2; |
| 924 |
|
| 925 |
$queue_item = [ |
| 926 |
'column' => $col, |
| 927 |
'data_type' => $data_type, |
| 928 |
'byte_offset' => 0, |
| 929 |
'total_length' => $value_length, |
| 930 |
]; |
| 931 |
if ($this->row_reader->is_character_string_type($data_type)) { |
| 932 |
$queue_item['character_offset'] = 0; |
| 933 |
} |
| 934 |
$this->oversized_queue[] = $queue_item; |
| 935 |
} |
| 936 |
} |
| 937 |
|
| 938 |
if ($excess > 0 && !empty($unchunkable_data_types)) { |
| 939 |
$unchunkable_data_type = key($unchunkable_data_types); |
| 940 |
// phpcs:disable WordPress.Security.EscapeOutput.ExceptionNotEscaped -- Protocol error returned as authenticated API data, never HTML. |
| 941 |
throw new \RuntimeException( |
| 942 |
"Row in table " . $this->row_reader->quote_identifier($this->row_reader->get_current_table()) . |
| 943 |
" cannot use UPDATE ... CONCAT() chunks for data type {$unchunkable_data_type}." |
| 944 |
); |
| 945 |
// phpcs:enable WordPress.Security.EscapeOutput.ExceptionNotEscaped |
| 946 |
} |
| 947 |
|
| 948 |
if ( |
| 949 |
$projected_statement_size - $saved_bytes > |
| 950 |
$maximum_insert_statement_bytes || |
| 951 |
$projected_fragment_size - $saved_bytes > |
| 952 |
self::MAX_SQL_PART_BODY_BYTES |
| 953 |
) { |
| 954 |
// phpcs:disable WordPress.Security.EscapeOutput.ExceptionNotEscaped -- Protocol error returned as authenticated API data, never HTML. |
| 955 |
throw new \RuntimeException( |
| 956 |
"Row in table " . $this->row_reader->quote_identifier($this->row_reader->get_current_table()) . |
| 957 |
" cannot fit the SQL size limits with the available UPDATE chunking." . |
| 958 |
" max_statement_size is {$this->max_statement_size}" . |
| 959 |
" bytes and the SQL part body limit is " . self::MAX_SQL_PART_BODY_BYTES . " bytes." |
| 960 |
); |
| 961 |
// phpcs:enable WordPress.Security.EscapeOutput.ExceptionNotEscaped |
| 962 |
} |
| 963 |
|
| 964 |
if (empty($chunked_columns)) { |
| 965 |
$this->oversized_pk_values = null; |
| 966 |
} |
| 967 |
|
| 968 |
$formatted_values = []; |
| 969 |
foreach ($this->row_reader->get_current_column_names() as $col) { |
| 970 |
if (isset($chunked_columns[$col])) { |
| 971 |
$formatted_values[$col] = "''"; |
| 972 |
continue; |
| 973 |
} |
| 974 |
$data_type = $this->row_reader->get_data_type($col); |
| 975 |
$formatted_values[$col] = $this->format_value($raw_values[$col], $data_type); |
| 976 |
} |
| 977 |
|
| 978 |
return "(" . implode(",", array_values($formatted_values)) . ")"; |
| 979 |
} |
| 980 |
|
| 981 |
/** Returns the exact SQL bytes used by one formatted VALUES tuple. */ |
| 982 |
private function estimate_formatted_row_tuple_bytes($row) |
| 983 |
{ |
| 984 |
$tuple_bytes = 2; |
| 985 |
$column_index = 0; |
| 986 |
foreach ($this->row_reader->get_current_column_names() as $column) { |
| 987 |
if ($column_index > 0) { |
| 988 |
++$tuple_bytes; |
| 989 |
} |
| 990 |
$tuple_bytes += $this->estimate_formatted_size( |
| 991 |
$row[$column] ?? null, |
| 992 |
$this->row_reader->get_data_type($column) |
| 993 |
); |
| 994 |
++$column_index; |
| 995 |
} |
| 996 |
return $tuple_bytes; |
| 997 |
} |
| 998 |
|
| 999 |
/** |
| 1000 |
* Computes the maximum raw byte size of each chunk for the given column, |
| 1001 |
* such that an UPDATE ... SET col = CONCAT(col, FROM_BASE64('...')) |
| 1002 |
* statement stays within both SQL size limits. |
| 1003 |
*/ |
| 1004 |
private function compute_chunk_size($column) |
| 1005 |
{ |
| 1006 |
$quoted_table = $this->row_reader->quote_identifier($this->row_reader->get_current_table()); |
| 1007 |
$quoted_column = $this->row_reader->quote_identifier($column); |
| 1008 |
$update_overhead = strlen("UPDATE {$quoted_table} SET {$quoted_column} = CONCAT({$quoted_column}, ) WHERE ;"); |
| 1009 |
$where_clause_size = $this->estimate_pk_where_size(); |
| 1010 |
$total_overhead = $update_overhead + $where_clause_size + 100; // Extra margin |
| 1011 |
|
| 1012 |
$maximum_update_statement_size = min( |
| 1013 |
$this->max_statement_size, |
| 1014 |
self::MAX_SQL_PART_BODY_BYTES |
| 1015 |
); |
| 1016 |
$max_chunk_raw_size = ($maximum_update_statement_size - $total_overhead); |
| 1017 |
|
| 1018 |
// Base64 inflates by ~1.33x, plus FROM_BASE64('') wrapper overhead |
| 1019 |
$max_chunk_raw_size = (int)(($max_chunk_raw_size - 20) / 1.34); |
| 1020 |
return max($max_chunk_raw_size, 1000); |
| 1021 |
} |
| 1022 |
|
| 1023 |
/** Rough strlen() estimate for the WHERE pk1 = v1 AND pk2 = v2 clause. */ |
| 1024 |
private function estimate_pk_where_size() |
| 1025 |
{ |
| 1026 |
if (!$this->oversized_pk_values) { |
| 1027 |
/** |
| 1028 |
* A wild guess. 1KB is probably more than necessary, but we're trying to stay |
| 1029 |
* on the safe side. |
| 1030 |
*/ |
| 1031 |
return 1024; |
| 1032 |
} |
| 1033 |
|
| 1034 |
$size = 0; |
| 1035 |
foreach ($this->oversized_pk_values as $col => $value) { |
| 1036 |
$size += strlen($this->row_reader->build_comparison($col, $value, "=")); |
| 1037 |
$size += 5; // AND |
| 1038 |
} |
| 1039 |
|
| 1040 |
return (int)$size; |
| 1041 |
} |
| 1042 |
|
| 1043 |
/** |
| 1044 |
* Emits one UPDATE ... SET col = CONCAT(col, chunk) statement. |
| 1045 |
* |
| 1046 |
* Instead of storing the entire column value in memory, this method |
| 1047 |
* re-reads just the needed chunk from the database using SUBSTRING(). |
| 1048 |
* This keeps the cursor tiny (byte offsets only) while still producing |
| 1049 |
* the correct UPDATE statements. |
| 1050 |
* |
| 1051 |
* Returns false when the queue is drained so the next INSERT can begin. |
| 1052 |
*/ |
| 1053 |
private function emit_oversized_update() |
| 1054 |
{ |
| 1055 |
if (empty($this->oversized_queue)) { |
| 1056 |
$this->state = self::STATE_START_INSERT; |
| 1057 |
$this->oversized_pk_values = null; |
| 1058 |
return false; |
| 1059 |
} |
| 1060 |
|
| 1061 |
$current = $this->oversized_queue[0]; |
| 1062 |
$column = $current['column']; |
| 1063 |
$data_type = $current['data_type']; |
| 1064 |
$byte_offset = $current['byte_offset']; |
| 1065 |
$total_length = $current['total_length']; |
| 1066 |
|
| 1067 |
$chunk_size = $this->compute_chunk_size($column); |
| 1068 |
|
| 1069 |
// MySQL SUBSTRING() counts characters for character strings, while |
| 1070 |
// $chunk_size is a byte budget. Every requested character may use the |
| 1071 |
// column character set's maximum byte length, so a fixed amount of |
| 1072 |
// spare space would not bound the result. Divide the byte budget by |
| 1073 |
// that per-character maximum to keep the raw chunk within its limit |
| 1074 |
// without splitting a character. Binary strings continue in bytes. |
| 1075 |
$character_string = $this->row_reader->is_character_string_type($data_type); |
| 1076 |
if ($character_string) { |
| 1077 |
$value_offset = $current['character_offset']; |
| 1078 |
$value_length = max( |
| 1079 |
1, |
| 1080 |
integer_divide( |
| 1081 |
$chunk_size, |
| 1082 |
$this->row_reader->get_maximum_character_bytes($column) |
| 1083 |
) |
| 1084 |
); |
| 1085 |
} else { |
| 1086 |
$value_offset = $byte_offset; |
| 1087 |
$value_length = min($chunk_size, $total_length - $byte_offset); |
| 1088 |
} |
| 1089 |
|
| 1090 |
$chunk_result = $this->fetch_value_substring_from_the_current_oversized_row( |
| 1091 |
$column, |
| 1092 |
$value_offset + 1, |
| 1093 |
$value_length, |
| 1094 |
$character_string |
| 1095 |
); |
| 1096 |
$chunk = $chunk_result['value']; |
| 1097 |
$chunk_bytes = strlen($chunk); |
| 1098 |
|
| 1099 |
if ($chunk_bytes === 0 && $byte_offset < $total_length) { |
| 1100 |
// phpcs:disable WordPress.Security.EscapeOutput.ExceptionNotEscaped -- Protocol error returned as authenticated API data, never HTML. |
| 1101 |
throw new \RuntimeException( |
| 1102 |
"Oversized column " . |
| 1103 |
$this->row_reader->quote_identifier($this->row_reader->get_current_table()) . "." . |
| 1104 |
$this->row_reader->quote_identifier($column) . |
| 1105 |
" returned an empty chunk at byte offset {$byte_offset} before its saved" . |
| 1106 |
" {$total_length}-byte length. The source value changed during export;" . |
| 1107 |
" run db-pull --abort and start again." |
| 1108 |
); |
| 1109 |
// phpcs:enable WordPress.Security.EscapeOutput.ExceptionNotEscaped |
| 1110 |
} |
| 1111 |
if ($chunk_bytes > $total_length - $byte_offset) { |
| 1112 |
// phpcs:disable WordPress.Security.EscapeOutput.ExceptionNotEscaped -- Protocol error returned as authenticated API data, never HTML. |
| 1113 |
throw new \RuntimeException( |
| 1114 |
"Oversized column " . |
| 1115 |
$this->row_reader->quote_identifier($this->row_reader->get_current_table()) . "." . |
| 1116 |
$this->row_reader->quote_identifier($column) . |
| 1117 |
" returned {$chunk_bytes} bytes at byte offset {$byte_offset}, beyond its" . |
| 1118 |
" saved {$total_length}-byte length. The source value changed during export;" . |
| 1119 |
" run db-pull --abort and start again." |
| 1120 |
); |
| 1121 |
// phpcs:enable WordPress.Security.EscapeOutput.ExceptionNotEscaped |
| 1122 |
} |
| 1123 |
|
| 1124 |
$formatted_chunk = $this->format_value($chunk, $data_type); |
| 1125 |
|
| 1126 |
$where_parts = []; |
| 1127 |
foreach ($this->oversized_pk_values as $pk_col => $pk_value) { |
| 1128 |
$where_parts[] = $this->row_reader->build_comparison($pk_col, $pk_value, "="); |
| 1129 |
} |
| 1130 |
$where_clause = implode(" AND ", $where_parts); |
| 1131 |
|
| 1132 |
$quoted_table = $this->row_reader->quote_identifier($this->row_reader->get_current_table()); |
| 1133 |
$quoted_column = $this->row_reader->quote_identifier($column); |
| 1134 |
$sql = "UPDATE {$quoted_table} SET {$quoted_column} = CONCAT({$quoted_column}, {$formatted_chunk}) WHERE {$where_clause};"; |
| 1135 |
|
| 1136 |
$this->current_sql_fragment = $sql; |
| 1137 |
|
| 1138 |
$this->oversized_queue[0]['byte_offset'] += $chunk_bytes; |
| 1139 |
if ($character_string) { |
| 1140 |
$this->oversized_queue[0]['character_offset'] += $chunk_result['value_length']; |
| 1141 |
} |
| 1142 |
if ($this->oversized_queue[0]['byte_offset'] >= $total_length) { |
| 1143 |
array_shift($this->oversized_queue); |
| 1144 |
} |
| 1145 |
|
| 1146 |
return true; |
| 1147 |
} |
| 1148 |
|
| 1149 |
/** |
| 1150 |
* Fetches a substring of a column value from the current table using |
| 1151 |
* the oversized row's primary key values. |
| 1152 |
* |
| 1153 |
* Character strings use character ranges so a chunk never cuts a |
| 1154 |
* multibyte character. Binary strings cast before SUBSTRING so their |
| 1155 |
* ranges count bytes. Both return raw bytes for base64 encoding. |
| 1156 |
* |
| 1157 |
* @return array { |
| 1158 |
* Fetched substring details. |
| 1159 |
* |
| 1160 |
* @type string $value Raw substring bytes. |
| 1161 |
* @type int $value_length Length in characters or bytes, matching the requested range. |
| 1162 |
* } |
| 1163 |
*/ |
| 1164 |
private function fetch_value_substring_from_the_current_oversized_row( |
| 1165 |
string $column, |
| 1166 |
int $start, |
| 1167 |
int $length, |
| 1168 |
bool $character_string |
| 1169 |
): array { |
| 1170 |
$quoted_table = $this->row_reader->quote_identifier($this->row_reader->get_current_table()); |
| 1171 |
$quoted_column = $this->row_reader->quote_identifier($column); |
| 1172 |
|
| 1173 |
$where_parts = []; |
| 1174 |
foreach ($this->oversized_pk_values as $pk_col => $pk_value) { |
| 1175 |
$where_parts[] = $this->row_reader->build_comparison($pk_col, $pk_value, "="); |
| 1176 |
} |
| 1177 |
$where_clause = implode(" AND ", $where_parts); |
| 1178 |
|
| 1179 |
$value_expression = $character_string |
| 1180 |
? "SUBSTRING({$quoted_column}, {$start}, {$length})" |
| 1181 |
: "SUBSTRING(CAST({$quoted_column} AS BINARY), {$start}, {$length})"; |
| 1182 |
$sql = "SELECT CAST({$value_expression} AS BINARY) AS value_chunk," |
| 1183 |
. " CHAR_LENGTH({$value_expression}) AS value_length" |
| 1184 |
. " FROM {$quoted_table} WHERE {$where_clause}"; |
| 1185 |
$stmt = $this->db->prepare($sql); |
| 1186 |
$stmt->execute(); |
| 1187 |
$result = $stmt->fetch(PdoConstants::fetch_assoc()); |
| 1188 |
|
| 1189 |
if ($result === false) { |
| 1190 |
throw new \RuntimeException( |
| 1191 |
"Failed to fetch column substring for oversized row: {$column}" |
| 1192 |
); |
| 1193 |
} |
| 1194 |
|
| 1195 |
return [ |
| 1196 |
'value' => $result['value_chunk'], |
| 1197 |
'value_length' => (int) $result['value_length'], |
| 1198 |
]; |
| 1199 |
} |
| 1200 |
|
| 1201 |
/** @return bool */ |
| 1202 |
private function has_pending_oversized_updates() |
| 1203 |
{ |
| 1204 |
return !empty($this->oversized_queue); |
| 1205 |
} |
| 1206 |
} |
| 1207 |
|
