Title: It doesn’t work with multisite and causes data duplication errors. Last modified: September 22, 2026 --- # It doesn’t work with multisite and causes data duplication errors. * Resolved [Phuong Tong](https://wordpress.org/support/users/tvphuong41/) * (@tvphuong41) * [1 week, 2 days ago](https://wordpress.org/support/topic/it-doesnt-work-with-multisite-and-causes-data-duplication-errors/) * It doesn’t work with multisite and causes data duplication errors. * My second website appears as the first site on the menu, even though I used a prefix in wp-config.php. Viewing 12 replies - 1 through 12 (of 12 total) * Plugin Author [laruence](https://wordpress.org/support/users/laruence/) * (@laruence) * [1 week, 1 day ago](https://wordpress.org/support/topic/it-doesnt-work-with-multisite-and-causes-data-duplication-errors/#post-19026764) * you should define different prefix for different site, for example, site 1: uses wp1_, site 2 uses: wp2_ * Thread Starter [Phuong Tong](https://wordpress.org/support/users/tvphuong41/) * (@tvphuong41) * [1 week, 1 day ago](https://wordpress.org/support/topic/it-doesnt-work-with-multisite-and-causes-data-duplication-errors/#post-19026793) * I am referring to WordPress Multisite, not separate, individual WordPress installations. With WordPress Multisite/Network, I cannot add multiple prefixes like `wp1_`,` wp2_`, `wp3_`, etc. Could you integrate a feature to automatically add IDs for Multisite? * [flytomoon](https://wordpress.org/support/users/flytomoon/) * (@flytomoon) * [1 week, 1 day ago](https://wordpress.org/support/topic/it-doesnt-work-with-multisite-and-causes-data-duplication-errors/#post-19026796) * yes, it’s a reasonable feature. - This reply was modified 1 week, 1 day ago by [flytomoon](https://wordpress.org/support/users/flytomoon/). * Plugin Author [laruence](https://wordpress.org/support/users/laruence/) * (@laruence) * [1 week, 1 day ago](https://wordpress.org/support/topic/it-doesnt-work-with-multisite-and-causes-data-duplication-errors/#post-19026810) * working on it. * Thread Starter [Phuong Tong](https://wordpress.org/support/users/tvphuong41/) * (@tvphuong41) * [1 week, 1 day ago](https://wordpress.org/support/topic/it-doesnt-work-with-multisite-and-causes-data-duplication-errors/#post-19026812) * Thank you so much for creating such a fantastic plugin. I feel like my website loads faster than before. Thanks again. * Plugin Author [laruence](https://wordpress.org/support/users/laruence/) * (@laruence) * [1 week, 1 day ago](https://wordpress.org/support/topic/it-doesnt-work-with-multisite-and-causes-data-duplication-errors/#post-19026833) * You’re welcome — and thank you for the report. * 1.4.0 is out, and it does exactly what you asked for: on multisite the cache prefix now automatically carries the current blog id, so each blog gets its own namespace and they no longer read each other’s entries. No more manual `wp1_`/` wp2_` per site. * One honest caveat: my own blog (laruence.com) is not a multisite, so I could only test this on a temporary multisite install. The implementation is straightforward, but I’d appreciate it if you could try 1.4.0 on your network and let me know whether the duplication issue is gone. * Thanks again for the feedback! * Thread Starter [Phuong Tong](https://wordpress.org/support/users/tvphuong41/) * (@tvphuong41) * [1 week, 1 day ago](https://wordpress.org/support/topic/it-doesnt-work-with-multisite-and-causes-data-duplication-errors/#post-19027522) * I set `yac.values_memory_size` to 100M, but I notice the statistics in the dashboard now show usage exceeding 100M; will this cause any issues? Here is my `wp-config` setup:define( ‘YAC_OCACHE_KEY_PREFIX’, ‘tut’ );define( ‘YAC_OCACHE_EMPTY_TTL’, 21600 );define( ‘YAC_OCACHE_DISABLE’, false ); * Plugin Author [laruence](https://wordpress.org/support/users/laruence/) * (@laruence) * [1 week, 1 day ago](https://wordpress.org/support/topic/it-doesnt-work-with-multisite-and-causes-data-duplication-errors/#post-19027604) *  hmm, don’t worry — this is most likely a bug in my **stats/admin display logic**, not in the cache itself. The admin panel statistics are computed from `Yac::dump()`, which scans _all_ entries in the shared memory pool; the cache read/write path is not affected by this. I will review the stats code tomorrow and follow up here. * One more suggestion while you’re at it: set both `yac.keys_memory_size` and ` yac.values_memory_size` to powers of two, e.g. 64M / 128M. Yac rounds the shared- memory segment sizes down to a power of two internally, so non-power-of-two values just waste the difference. * Thread Starter [Phuong Tong](https://wordpress.org/support/users/tvphuong41/) * (@tvphuong41) * [1 week ago](https://wordpress.org/support/topic/it-doesnt-work-with-multisite-and-causes-data-duplication-errors/#post-19027828) * Thank you for the reminder; I will reinstall it. * Plugin Author [laruence](https://wordpress.org/support/users/laruence/) * (@laruence) * [1 week ago](https://wordpress.org/support/topic/it-doesnt-work-with-multisite-and-causes-data-duplication-errors/#post-19027880) * I think I know why. One thing to confirm first: does your dashboard show Recycles above zero? * When the value pool fills up, Yac wraps around and overwrites it from the start. Entries whose blocks were overwritten stay in the slot table — a slot is only freed by a kick or a TTL expiry — so dump() still reports them, each carrying the size of a block that no longer exists. Summing those counts the same bytes twice. * So: a stats bug, not a cache bug. Nothing incorrect is served — Yac validates each block by CRC, so a recycled entry reads back as a plain miss, never stale data. Fixed on the plugin side; I’ll probably hold off on a release until I’ve accumulated a few more fixes, so this one won’t reach you in a version right away. * Your pool is genuinely full, so two suggestions: 1. Lower yac.compress_threshold to 1024. Compression is already on by default at 4096; this makes 1K–4K values compress too. It’s PHP_INI_SYSTEM, so php.ini, not wp-config.php. 2. Raise yac.values_memory_size. Recycles mean live entries are evicted early, so more memory buys real hit rate. * - This reply was modified 1 week ago by [laruence](https://wordpress.org/support/users/laruence/). * Thread Starter [Phuong Tong](https://wordpress.org/support/users/tvphuong41/) * (@tvphuong41) * [1 week ago](https://wordpress.org/support/topic/it-doesnt-work-with-multisite-and-causes-data-duplication-errors/#post-19028249) * Thank you. I’ll try adjusting the settings and wait for the new version; it feels faster than other Object Cache plugins. * Plugin Author [laruence](https://wordpress.org/support/users/laruence/) * (@laruence) * [1 week ago](https://wordpress.org/support/topic/it-doesnt-work-with-multisite-and-causes-data-duplication-errors/#post-19028260) * Yes, benchmark says it is above 10x faster than apcu, 100x faster than memcached( local http). [laruence/yac: Ultra-fast, lock-free shared-memory user-data cache for PHP](https://github.com/laruence/yac#benchmarks) 🙂 Viewing 12 replies - 1 through 12 (of 12 total) You must be [logged in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Fit-doesnt-work-with-multisite-and-causes-data-duplication-errors%2F%3Foutput_format%3Dmd&locale=en_US) to reply to this topic. * ![](https://ps.w.org/yac-object-cache/assets/icon-256x256.png?rev=3677662) * [Yac Object Cache](https://wordpress.org/plugins/yac-object-cache/) * [Frequently Asked Questions](https://wordpress.org/plugins/yac-object-cache/#faq) * [Support Threads](https://wordpress.org/support/plugin/yac-object-cache/) * [Active Topics](https://wordpress.org/support/plugin/yac-object-cache/active/) * [Unresolved Topics](https://wordpress.org/support/plugin/yac-object-cache/unresolved/) * [Reviews](https://wordpress.org/support/plugin/yac-object-cache/reviews/) * 12 replies * 3 participants * Last reply from: [laruence](https://wordpress.org/support/users/laruence/) * Last activity: [1 week ago](https://wordpress.org/support/topic/it-doesnt-work-with-multisite-and-causes-data-duplication-errors/#post-19028260) * Status: resolved