sqlite-object-cache / readme.txt

readme.txt in SQLite Object Cache 1.6.0, at readme.txt

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1	=== SQLite Object Cache ===
2	Author: Oliver Jones
3	Contributors: OllieJones
4	Tags: cache, object cache, sqlite, performance, apcu
5	Requires at least: 5.5
6	Requires PHP: 5.6
7	Tested up to: 6.9
8	Version: 1.6.0
9	Stable tag: 1.6.0
10	License: GPLv2 or later
11	License URI: http://www.gnu.org/licenses/gpl-2.0.html
12	Github Plugin URI: https://github.com/OllieJones/sqlite-object-cache
13	Primary Branch: trunk
14	Text Domain: sqlite-object-cache
15	Domain Path: /languages/
16	Donate link: https://github.com/sponsors/OllieJones
17
18
19	A fast persistent object cache backend for the rest of us, powered by SQLite and accelerated by APCu
20
21	== Description ==
22
23	A [persistent object cache](https://developer.wordpress.org/reference/classes/wp_object_cache/#persistent-cache-plugins) helps your site perform well. This one uses the widely available [SQLite3](https://www.php.net/manual/en/book.sqlite3.php) extension, and optionally the [igbinary](https://www.php.net/manual/en/intro.igbinary.php) and [APCu](https://www.php.net/manual/en/book.apcu.php) extensions to php. Many hosting services offer those extensions, and they are easy to install on a server you control.
24
25	<h4>What is this about?</h4>
26
27	It's about making your site's web server perform better. An object cache does that by reducing the workload on your MariaDB or MySQL database. This is not a [page cache](https://developer.wordpress.org/advanced-administration/performance/cache/); these persistent objects go into a different kind of cache. These objects aren't chunks of web pages ready for people to view in their browsers, they are data objects for use by the WordPress software.
28
29	[Caches](https://en.wikipedia.org/wiki/Cache_(computing)) are ubiquitous in computing, and WordPress has its own caching subsystem. Caches contain short-term copies of the results of expensive database lookups or computations, and allow software to use the copy rather than repeating the expensive operation. This plugin (like other object-caching plugins) extends WordPress's caching subsystem to save those short-term copies from page view to page view. WordPress's cache happens to be a [memoization](https://en.wikipedia.org/wiki/Cache_(computing)#Memoization) cache.
30
31	Without a persistent object cache, every WordPress page view must use your MariaDB or MySQL database server to retrieve everything about your site. When a user requests a page, WordPress starts from scratch and loads everything it needs from your database server. Only then can it deliver content to your user. With a persistent object cache, WordPress immediately loads much of the information it needs. This lightens the load on your database server and delivers content to your users faster.
32
33	<h4>Who should use this?</h4>
34
35	If your site runs on a single web server machine, and that server provides the [SQLite3](https://www.php.net/manual/en/book.sqlite3.php) and [igbinary](https://www.php.net/manual/en/intro.igbinary.php) extensions to php, this plugin will almost certainly make your site work faster. And if that server provides the [APCu](https://www.php.net/manual/en/book.apcu.php) extension, this plugin uses it too.
36
37	Some hosting providers offer [redis](https://redis.io/) cache servers. If your provider offers redis, it may be a good choice. You can use it via the [Redis Object Cache](https://wordpress.org/plugins/redis-cache/) plugin. Sites using redis have one SQL database and another non-SQL storage server: redis. Other hosting providers offer [memcached](https://memcached.org/), which has the [Memcached Object Cache](https://wordpress.org/plugins/memcached/) plugin. And some large multipurpose cache plugins, such as the [LiteSpeed Cache](https://wordpress.org/plugins/litespeed-cache/), also offer object caching based on one of those cache server software packages.
38
39	The cache-server approach to object caching comes into its own when you have multiple load-balanced web server machines handling your site. SQLite doesn't work correctly in a multiple-web-server environment.
40
41	But, for single-server site configurations, SQLite, possibly assisted by APCu, performs well. And the vast majority of sites are single-server.
42
43	<h4>APCu</h4>
44
45	[APCu](https://www.php.net/manual/en/book.apcu.php) is an in-memory storage medium. It lets php programs, like WordPress, store data in shared memory so it's very fast to retrieve when needed. If APCu is available on your host server, you can configure this plugin to use it. It reduces the typical cache lookup time to one-fifth or less of the SQLite lookup time, which is itself a few tens of microseconds. Performance counts, especially on busy web sites.
46
47	Please look at [Installation](https://wordpress.org/plugins/sqlite-object-cache/#installation) to learn how to configure this plugin to use APCu. The plugin works fast without it, and faster with it.
48
49	WP-CLI: Even if APCu is in use, caching with SQLite is necessary when your web site uses WP-CLI, because WP-CLI programs do not have access to the APCu cache. This plugin writes all cached data both to APCu and to SQLite and makes sure the two are synchronized.
50
51	<h4>WP-CLI</h4>
52
53	You can control this plugin via WP-CLI once you activate it. Please type this command into your shell for details.
54
55	`wp help sqlite-object-cache`
56
57	<h4>Credits</h4>
58
59	Thanks to [Till Krüss](https://profiles.wordpress.org/tillkruess/). His [Redis Object Cache](https://wordpress.org/plugins/redis-cache/) plugin serves as a model for this one. And thanks to [Ari Stathopoulos](https://profiles.wordpress.org/aristath/) and [Jonny Harris](https://profiles.wordpress.org/spacedmonkey/) for reviewing this. Props to Matt Jones for finding and fixing a bug that appeared on a heavily loaded system. Thanks to [Massimo Villa](https://speedable.net/about-us/) for testing help, and to [nickchomey](https://github.com/nickchomey) for a comprehensive code review. All defects are, of course, entirely the author's responsibility.
60
61	And thanks to Jetbrains for the use of their software development tools, especially [PhpStorm](https://www.jetbrains.com/phpstorm/). It's hard to imagine how a plugin like this one could be developed without PhpStorm's tools for exploring epic code bases like WordPress's.
62
63	<h4>How can I learn more about making my WordPress site more efficient?</h4>
64
65	We offer several plugins to help with your site's database efficiency. You can [read about them here](https://www.plumislandmedia.net/wordpress/performance/optimizing-wordpress-database-servers/).
66
67	== Installation ==
68
69	For this plugin to work for you, your server must have the [SQLite3](https://www.php.net/manual/en/book.sqlite3.php) extension to php installed.
70
71	If you have the [igbinary](https://www.php.net/manual/en/intro.igbinary.php) and [APCu](https://www.php.net/manual/en/book.apcu.php) extensions, this plugin uses them to work more efficiently. But it works without them.
72
73	Installing "SQLite Object Cache" can be done either by searching for "SQLite Object Cache" via the "Plugins > Add New" screen in your WordPress dashboard, or by using the following steps:
74
75	1. Download the plugin via WordPress.org
76	1. Upload the ZIP file through the 'Plugins > Add New > Upload' screen in your WordPress dashboard
77	1. Activate the plugin through the 'Plugins' menu in WordPress
78
79	Or, use these WP-CLI commands to install the plugin, secure it, activate it, and set the cache size to 32MiB.
80
81	`wp plugin install sqlite-object-cache
82	wp config set WP_CACHE_KEY_SALT $(openssl rand -base64 12)
83	wp plugin activate sqlite-object-cache
84	wp sqlite-object-cache size 32`
85
86	The plugin offers a few optional settings for your `wp-config.php` file. Do not change them while the plugin is activated. If you change them, deactivate the plugin first, then change them, then reactivate the plugin.
87
88	* WP_SQLITE_OBJECT_CACHE_SERIALIZE. When true, this forces the plugin to use 's [serialize()](https://www.php.net/manual/en/function.serialize.php) scheme to store cached data in SQLite. If this is not set, the plugin uses the more efficient [igbinary](https://www.php.net/manual/en/function.igbinary-serialize.php) scheme if it is available.
89	* WP_SQLITE_OBJECT_CACHE_DB_FILE. This is the SQLite file pathname. The default is `…/wp-content/.ht.object_cache.sqlite`. Use this if you want to place the SQLite cache file outside your document root.
90	* WP_SQLITE_OBJECT_CACHE_TIMEOUT. This is the SQLite timeout in milliseconds. Default: 5000. (Notice that the times shown in the Statistics tab are in microseconds if you compare them to this timeout setting.)
91	* WP_SQLITE_OBJECT_CACHE_JOURNAL_MODE. This is the [SQLite journal mode](https://www.sqlite.org/pragma.html#pragma_journal_mode). Default: ‘WAL’. Possible values DELETE \| TRUNCATE \| PERSIST \| MEMORY \| WAL \| WAL2 \| NONE. (Not all SQLite3 implementations handle WAL2.)
92	* WP_SQLITE_OBJECT_CACHE_APCU. If true enables cache acceleration with APCu RAM. This setting can be updated from the plugin's Settings page.
93	* WP_CACHE_KEY_SALT. Set this to a hard-to-guess random value to make your cache keys harder to guess. This setting works for other cache plugins as well.
94
95	<h4>Configuring the cache key salt</h4>
96
97	When multiple sites share the same server hardware and software, they can sometimes share the same cache data. Setting `WP_CACHE_KEY_SALT` to a hard-to-guess random value for each site makes it much harder for one site to get another site's data. This works for other cache plugins too. Notice that this `WP_CACHE_KEY_SALT` value must be set, in your site's `wp-config.php` file, before activating any cache plugin, including page caches and persistent object caches.
98
99	To set the value put a line like this in `wp-config.php`.
100
101	`define( 'WP_CACHE_KEY_SALT', 'Random_t6xJix' );`
102
103	Of course, use your own random value, not the one in this example. You can get one from your Linux command line shell with the `openssl rand -base64 12`. Or, if you use WP-CLI you can set the value directly with
104
105	`wp config set WP_CACHE_KEY_SALT $(openssl rand -base64 12)`
106
107	<h4>Configuring and Using APCu</h4>
108
109	[APCu](https://www.php.net/manual/en/intro.apcu.php) is an in-memory storage medium. If APCu is available on your host server, you can configure this plugin to use it. There is an option to enable it on the plugin's Settings page. Or you can do it manually. Put a WP_SQLITE_OBJECT_CACHE_APCU value of `true` into your `wp-config.php` file. You can use this WP-CLI command to do that.
110
111	`wp config set --raw WP_SQLITE_OBJECT_CACHE_APCU true`
112
113	Or, you can edit your `wp-config.php` file to add this line.
114
115	`define( 'WP_SQLITE_OBJECT_CACHE_APCU', true );`
116
117	== Frequently Asked Questions ===
118
119	= Does this work with a multisite WordPress installation? =
120
121	Yes. To see the Settings page, choose Settings > Object Cache from the first site, or any site, in the multisite installation.
122
123	= How much faster will this make my site? =
124
125	Exactly predicting each site's speedup is not possible. Still, benchmarking results comparing it to other object caching schemes are promising. Please see [this](https://www.plumislandmedia.net/wordpress-plugins/sqlite-object-cache/benchmarks/). If you run a benchmark, please let the author know by leaving a comment on that page or using the [support forum](https://wordpress.org/support/plugin/sqlite-object-cache/).
126
127	= What Cached Data Size should I use for my site? =
128
129	The default setting for Cached Data Size is 16 megabytes (MiB). This plugin allows the actual cached data size to grow larger than that, and occasionally removes old -- the least recently updated -- data to trim back the size to the setting. Take a look at the Statistics page. If your actual cached data usage under All Groups is consistently larger than the setting, double the setting.
130
131	If you operate a large and busy site, try an initial setting of 32 MiB, then adjust it based on the growth of the actual size.
132
133	Notice that this setting controls the size of the data in the cache. That is the size shown under All Groups. The data file used by SQLite is larger than that.
134
135	= What is SQLite? =
136
137	[SQLite](https://www.sqlite.org/about.html) is fast and efficient database software. It doesn't require a separate server. Instead, it is built into php using the [SQLite3](https://www.php.net/manual/en/book.sqlite3.php) extension. SQLite programs don't need to open network connections to send requests and wait for replies.
138
139	= What is igbinary? =
140
141	[igbinary](https://www.php.net/manual/en/ref.igbinary.php) is a php extension that provides an efficient way to serialize and compress the kinds of data objects stored in caches. It, in some cases, uses less than half the storage space of the built-in php data [serializer](https://www.php.net/manual/en/function.serialize.php). If igbinary is available in your php configuration, this plugin uses it, unless you force it not to by setting `WP_SQLITE_OBJECT_CACHE_SERIALIZE` to `true` in `wp-config.php`.
142
143	= What is APCu? =
144
145	[APCu](https://www.php.net/manual/en/book.apcu.php) is php extension offering an in-memory storage medium. You can configure this plugin to use it to speed up cache lookups.
146
147	= On my server the APCu shared memory cache is too small. How can I make it bigger? =
148
149	On most operating systems the size of the APCu cache is, as installed, 32MiB. If you need to increase this size you can add a line to your `php.ini` file mentioning the [apc.shm_size](https://www.php.net/manual/en/apcu.configuration.php#ini.apcu.shm-size) configuration option. For example, the line `apc.shm_size = 64M` sets the size to 64MiB. Please consult your operating system or hosting provider documetation for information on how to do this.
150
151	Notice that sometimes multiple WordPress installations that run on the same server share the same APCu cache, so provide enough space for them all. And keep in mind that this plugin only uses APCu to accelerate its operations, so the consequences of setting its size too small are not great.
152
153	= Does this plugin replace MariaDB or MySQL with SQLite? =
154
155	No. Your MariaDB or MySQL database sql server still holds all your content. All your site's imports, exports, backups and other database operations continue to function normally. This plugin uses SQLite simply to hold named values. For example, a value named "post\|3" will hold a temporary, easy-to-retrieve cached copy of post number 3. When it needs that post, WordPress can fetch it quickly from SQLite.
156
157	= Wait, what? Do I really need two different kinds of SQL database? =
158
159	No, you don't. This plugin doesn't use SQLite as a full-fledged database server.
160
161	A persistent object cache needs some kind of storage mechanism. SQLite serves this plugin as a fast and simple key / value storage mechanism.
162
163	Some hosting providers offer the scalable high-performance [redis](https://redis.io/) cache server. You can use it via [Redis Object Cache](https://wordpress.org/plugins/redis-cache/) plugin. Sites using redis have one SQL database and another non-SQL storage scheme: redis. Some other hosting providers offer [memcached](https://memcached.org/), which has the [Memcached Object Cache](https://wordpress.org/plugins/memcached/).
164
165	But many hosting providers don't offer either redis or memcached, while they do offer SQLite. This plugin enables your site to use a persistent object cache even without a separate cache server. And, because everything happens within your web server, the performance is good.
166
167	= Is this plugin compatible with my page-caching plugin? =
168
169	Probably. Page caching and persistent object caching are completely separate functions in WordPress. But, some multi-feature caching plugins support optional object caching using redis or memcached. If that feature is enabled in your page cache plugin, you should not use this plugin.
170
171	You can find out whether your page-cache plugin also enables persistent object caching. Look at the Drop-in section of the Plugins -> Installed Plugins page. If it mentions the drop-in called "object-cache.php" then your page cache plugin is handling persistent object caching. You should disable that feature before using this plugin.
172
173	Users of this plugin have found that it works well with WP Rocket, LiteSpeed Cache, WP Total Cache, WP Super Cache, and WP Fastest Cache. It also works with Cloudflare and other content delivery networks. The author has not learned of any incompatibilities in this area. (If you find one please start a support topic!)
174
175	= Can I disable object caching for my backend dashboard or other pages or REST API operations I choose? =
176
177	No.
178
179	That's not how object caching works. It's different from page caching. It works at the level of individual database operations in the WordPress code, not at the level of whole pages.
180
181	= Is this plugin compatible with my version of MySQL or MariaDB? =
182
183	Yes. It does not require any specific database server version.
184
185	= Is this persistent object cache faster than Redis or memcached? =
186
187	Yes. Those cache servers require WordPress to make round-trip network requests, while this one does not. Many users have found this caching methodology to be fast.
188
189	= This cache uses a file on my server HDD/SSD, while redis and memcached use RAM. Isn't RAM faster? =
190
191	RAM is indeed faster. Modern server operating systems offer extensive page caching for files, and SQLite is designed to take advantage of that, so the data needed may already be in RAM. Using a separate cache server require the web server to issue network requests and wait for responses, whereas using SQLite does not.
192
193	= Why not use the site's main MariaDB or MySql database server for the object cache? =
194
195	In WordPress, as in many web frameworks, your database server is a performance bottleneck. Using some other mechanism for the object cache avoids adding to your database workload. Web servers serve pages using multiple php processes, and each process handles its own SQLite workload while updating a shared database file. That spreads the object-cache workload out over many processes rather than centralizing it.
196
197	= Do I have to back up the data in SQLite? =
198
199	No. It's a cache, and everything in it is ephemeral. When WordPress cannot find what it needs in the cache, it simply recomputes it or refetches it from the database.
200
201	To avoid backing up SQLite files, tell your backup plugin to skip the files named `.sqlite`, `.sqlite-wal`, `.sqlite-wal2`, and `.sqlite-shm`.
202
203	This plugin automatically suppresses backing up your SQLite data when you use the [Updraft Plus](https://wordpress.org/plugins/updraftplus/), [BackWPUp](https://wordpress.org/plugins/backwpup/), or [WP STAGING](https://wordpress.org/plugins/wp-staging/) plugins. The [Duplicator](https://wordpress.org/plugins/duplicator/) plugin does not offer an automated way to suppress copying those files.
204
205	If you use some other backup or cloning plugin, please let the author know by creating a [support topic](https://wordpress.org/support/plugin/sqlite-object-cache/). It may be possible for this plugin to tell that plugin to skip backing up the SQLite files.
206
207	= If I already have another persistent object cache plugin, can I use this one? =
208
209	No. You only need one persistent object cache plugin, and WordPress only supports one.
210
211	= If I operate a scaled-up load-balanced installation, can I use this? =
212
213	No. If you have more than one web server this doesn't work correctly. If you operate at that scale, use redis or some other cache server. (If you aren't sure whether you have a load-balanced installation, you almost certainly do not.)
214
215	Please notice that SQLite does not work correctly if you put its files on a shared network drive (via CIFS, SMB, NFS, or some other drive sharing protocol).
216
217	= Can I use this with the Performance Lab plugin? =
218
219	Yes, but you must activate this plugin first before you activate [Performance Lab](https://wordpress.org/plugins/performance-lab/). And, you must deactivate Performance Lab before deactivating this plugin last.
220
221	The [Performance Lab plugin](https://wordpress.org/plugins/performance-lab/) offers some advanced and experimental ways of making your site faster. One of its features uses object-cache initialization code to start tracking performance. So there's a required order of activation if you want both to work.
222
223	= How can I use this object cache in my plugin or theme code to make it run faster? =
224
225	Easy. Use transients to store your cacheable data. WordPress's [Transient API](https://developer.wordpress.org/apis/transients/) uses persistent object caching if it's available, and the MariaDB or MySQL database when it isn't. The [Metadata API](https://developer.wordpress.org/apis/metadata/) and [Options API](https://developer.wordpress.org/apis/options/) also use persistent object caching.
226
227	= How does this work? =
228
229	This plugin uses a [WordPress drop-in](https://developer.wordpress.org/reference/functions/get_dropins/) to extend the functionality of the WP_Cache class. When you activate the plugin it creates the dropin file `.../wp-content/object-cache.php`. Upon deactivation, it removes that file and the cached data.
230
231	= Where does the plugin store the cached data? =
232
233	It's in your site's `wp_content` directory, in the file named `.ht.object-cache.sqlite`. That file's name has the `.ht.` prefix to prevent your web server from allowing it to be downloaded. SQLite also sometimes uses the files named `.ht.object-cache.sqlite-shm` and `.ht.object-cache.sqlite-wal`, so you may see any of those files.
234
235	You can make the plugin put its files at some other location by putting the pathname you want in `WP_SQLITE_OBJECT_CACHE_DB_FILE` in your `wp-config.php`.
236
237	On Linux and other UNIX-derived operating systems, you must give the command `ls -a` to see files when their names begin with a dot.
238
239	= I want to store my cached data in a more secure place. How do I do that?
240
241	Putting your .sqlite files outside your site's document root is good security practice. This is how you do it. If you define the constant `WP_SQLITE_OBJECT_CACHE_DB_FILE` in `wp_config.php` the plugin uses that for sqlite's file pathname instead. For example, if `wp-config.php` contains this line
242
243	`define( 'WP_SQLITE_OBJECT_CACHE_DB_FILE', '/tmp/mysite-object-cache.sqlite' );`
244
245	your object cache data goes into the `/tmp` folder in a file named `mysite-object-cache.sqlite`.
246
247	You can also define `WP_CACHE_KEY_SALT` to be a hard-to-guess text string. Continuing the example, this line
248
249	`define( 'WP_CACHE_KEY_SALT', 'qrstuv' );`
250
251	causes your object cache data to go into the `/tmp` folder in a file named `mysite-object-cache.qrstuv.sqlite`.
252
253	= Can this plugin use SQLite memory-mapped I/O?
254
255	Yes. You can use your OS's memory map feature to access and share cache data with [SQLite Memory-Mapped I/O](https://www.sqlite.org/mmap.html). On some server configurations this allows multiple php processes to share cached data more quickly. In the plugin this is disabled by default. You can enable it by telling the plugin how many MiB to use for memory mapping. For example, this wp-config setting tells the plugin to use 32MiB.
256
257	`define( 'WP_SQLITE_OBJECT_CACHE_MMAP_SIZE', 32 );`
258
259	Notice that using memory-mapped I/O may not help performance in the highly concurrent environment of a busy web server. That is why it is disabled by default. Notice also that this kind of memory-mapping is not the same thing as the APCu cache.
260
261	= I sometimes get timeout errors from SQLite. How can I fix them? =
262
263	Some sites occasionally generate error messages looking like this one:
264
265	`Unable to execute statement: database is locked in /var/www/wp-content/object-cache.php:1234`
266
267	This can happen if your server places your WordPress files on network-attached storage (that is, on a network drive). To solve this, store your cached data on a locally attached drive. See the question about storing your data in a more secure place. It also can happen in a very busy site.
268
269	Timeout errors can also happen if your Cached Data Size, or your site, is very large. Try reducing your Cached Data Size. If that doesn't help eliminate timeout errors, try setting the `WP_SQLITE_OBJECT_CACHE_TIMEOUT` parameter in your `wp-config.php` file to something larger than the default 5000 milliseconds.
270
271	= Why do I get errors when I use WP-CLI to administer my site? =
272
273	Sometimes [WP-CLI](https://wp-cli.org/) commands issued from a shell run with a different user from the web server. This plugin creates one or more object-cache files. An object-cache file may not be readable or writeable by the web server if it was created by the wp-cli user. Or the other way around.
274
275	On Linux, you can run your WP-CLI shell commands like this: `sudo -u www-data wp config list` This ensures they run with the same user as the web server.
276
277	= Does this plugin work with sites hosted on Microsoft Windows OSs with the IIS web server? =
278
279	Yes. But please be aware that users have reported cache corruption when using APCu. And please be sure to use the so-called "non thread safe" versions of php executables and DLLs.
280
281	= The Statistics display seems complex. What does it all mean? =
282
283	This plugin measures individual operations such as the time to look something up in the cache. It collects those individual measurements. The Statistics display analyzes them to show the fastest and slowest operations, the average operation, and other desciptive statistics.
284	Please [read this](https://www.plumislandmedia.net/wordpress-plugins/sqlite-object-cache/statistics-from-sqlite-object-cache/) for more information.
285
286	= Is there a joke somewhere in this? =
287
288	Q: What are the two hardest things to get right in computer science?
289
290	1. Caching things.
291	2. Naming things.
292	3. Coping with off-by-one errors.
293
294	Seriously, the core of WordPress has already worked out, over years of development and millions of sites, how to cache things and name them. This plugin, and the other persistent object cache plugins, simply extend that mechanism to make those things persistent.
295
296	= I have another question =
297
298	Please look for more questions and answers [here](https://www.plumislandmedia.net/wordpress-plugins/sqlite-object-cache/faq/). Or ask your question in the [support forum](https://wordpress.org/support/plugin/sqlite-object-cache/). If you start a support forum topic, please go to Tools->Site Health->Info, copy your site info from there and paste it into your support topic.
299
300	== Screenshots ==
301
302	1. Settings panel. Access it with Settings > Object Cache.
303	2. Performance statistics panel.
304
305
306	== Changelog ==
307
308	= 1.6.0 =
309
310	* Multisite: put the settings and statistics panels on the main site only.
311
312	= 1.5.7 =
313
314	* Flush the cache immediately after any software installation or upgrade operation.
315	* To eliminate state data delete all transients from the database on activation and deactivation.
316	* Add a Help tab and hyperlink to the statistics display.
317
318	= 1.5.6 =
319
320	* Fix a warning while generating diagnostic info.
321	* Update wp-config.php more robustly.
322
323	= 1.5.5 =
324
325	* Some diagnostic data now appears in Site Health - Info.
326	* The drop-in no longer attempts to load translations early, to eliminate an unterminated recursion.
327	* A problem with index creation on ancient SQLite versions is corrected.
328
329	= 1.5.4 =
330
331	* Handle non-persistent groups, get_multiple cache-misses, and MS-DOS line endings correctly.
332
333	= 1.5.2 =
334
335	* Correct a regression in object fetching (failure to clone when needed).
336	* Correct wrong display of Use APCu checkbox immediately after setting change
337
338	= 1.5.1 =
339
340	* Provide APCu opt-in on the settings page.
341
342	= 1.5.0 =
343
344	* Use APCu to increase performance if it is available and if WP_SQLITE_OBJECT_CACHE_APCU is defined.
345
346
347	== Upgrade Notice ==
348
349	The plugin now displays its settings and statistics panels only on the main site of a multisite installation.
350
351	The plugin now flushes the persistent cache immediately after any software installation or upgrade operation. It also deletes all transients from the MariaDB / MySQL database on activation and deactivation to get rid of stale data.
352
353	It presents a Help tab on the Statistics display showing an explanation.
354
355	Thanks, dear users for letting me know about defects you found, and for your patience as I figure this out. All remaining errors are solely the responsibility of the author.
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