PostgreSQL Index bloat under a microscope I've posted a snippet query to the PostgreSQL Wiki that "summarizes the keyspace" of a target B-Tree index. Compression tools on linux -- gzip vs bzip2 vs lzma vs compress. The postgres-wiki contains a view (extracted from a script of the bucardo project) to check for bloat in your database here For a quick reference you can check your table/index sizes regularly and check the no. Bloated indexes can slow down inserts and reduce lookup performance. check size of your tables and indexes: SELECT relname AS table_name, PostgreSQL index types and index bloating. > > > I'm not sure if this is a json issue or some other kind of issue. Index Bloat Across All Indexes. We have a product using PostgreSQL database server that is deployed at a couple of hundred clients. Mainly queries for detecting table bloat, index bloat, But some queries over pg_locks should be useful too. Don't run VACUUM FULL as a periodic maintenance task. As a PostgreSQL Database Administrator, there are the everyday expectations to check on backups, apply DDL changes, make sure the logs don’t have any game breaking ERROR’s, and answer panicked calls from developers who’s reports are running twice as long as normal and they have a meeting in ten minutes.. It is hard to say when an index is bloated, but if leaf_fragmentation exceeds 50-60, it's not so pretty. Is the old content being referred to still useful for people + online somewhere, or should the link be nuked? Connects to one or more Postgres databases and checks for a variety of things. Query is limited to all schema apart of postgres and to results where bloat_size is greater than 0. ACL on Linux -- POSIX Access control list on linux. Regards. Start with the show database bloat sample query on the PostgreSQL wiki if you're investigating possible table/index bloat issues. wiki and stackoverflow[*], I've discovered that the bloat is not, as was assumed, in the user tables, but in the system tables, mostly in pg_attributes and pg_class. Bloat in short, for those new to Postgres, is an unescapable by-product of Postgres’ excellent concurrency-enablement model called MVCC (multi-version concurrency control), that creates new copies of rows when you update data in a concurrent access scenario. Hey dear list, after a fex years of experiments and crash, I ended up with a grossly bloated postgres folder. bloated postgres data folder, clean up. I had about 8 Go of useless files. ACL on Linux -- setfacl examples. There are lot of useful queries (views), that are on our wiki. To reorganize an index, use REINDEX. To investigate possible causes for these really unusual bloat estimation numbers, we used the pgstattuple [object Object] When using the pg_upgrade link method to upgrade Postgres a major version. Re: Show_database_bloat reliability? Fillfactor can help you to speed up the process, but if autovacuum is not aggressive enough, you'll get very bloated table and bad performance soon. So in the next version we will introduce automated cleanup procedures which will gradually archive and DELETE old records during nightly batch jobs.. e.g. Monitor the bloat of indexes as both an absolute value (number of bytes) and as a percentage. Indexes will have to be rebuilt when they become too bloated. Some of them have gathered tens of gigabytes of data over the years. > I notice that you've got autovac nap time of 60 minutes, so it's possible you've managed to bloat your tables a fair bit. There is no index support for LIKE / ILIKE in PostgreSQL 8.4 - except for left anchored search terms. It is supposed to compute a rough estimate of the bloat for tables and indexes in a database. So, first, I'd suggest you to control your table's bloating … As the PostgreSQL wiki page says: This query is for informational purposes only. Also check whether autovacuum is enabled. [was: Re: REINDEX not working for wastedspace] at 2011-09-21 16:12:50 from Greg Smith Browse pgsql-performance by date This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. Linux. Install once per database: CREATE EXTENSION pg_trgm; It's my understanding that bloat can only appear through updates or deletes, but these partitions are reported to have significant bloat in them. You're on PostgreSQL 8.4 or older, where VACUUM FULL tends to bloat indexes. This index is in excellent shape (never used): It has only 14% bloat. > > Possibly your "bloat query" is failing to consider the toast table > associated with this table? (3 replies) I recently set up partitioning on a table that sees heavy insert traffic. Thanks to the various PostgreSQL environments we have under monitoring at Dalibo, these Btree bloat estimation queries keeps challenging me occasionally because of statistics deviation…or bugs. For Indexes its size in bytes and “pretty” form, extra size (extra pages are subtracted), index fill factor and the size of index bloat (same as with bloat for tables). Where else can this come from and how I can I reduce it? Since PostgreSQL 9.1 the additional module pg_trgm provides operator classes for GIN and GiST trigram indices supporting LIKE / ILIKE or regular expressions (operators ~ and friends). 4. Only certain tables were affected, pointing to problems with the tables themselves. See this wiki page for details. check_postgres is a script for monitoring various attributes of your database. I know using —link will use hard link pointers to the new data. Even with a good understanding of the health of managed databases, there … Btree bloat query - part 4. The query recursively performs a breadth-first search. > > which affects the calculation of the avg row size in the bloat query. For the table and index bloat estimations, we used queries based on the PostgreSQL Wiki’s database-bloat query. Some queries are necessary for maintenance, and I am thinking these queries should be integrated part of Postgres. yum -y install cpan cpan install YAML install Time::HiRes install Net::SMPP exit Use check_postgres or pgmetrics to get bloat estimates. Below are my > system specs and please find attached my postgresql configuration parameters > for current system. Action: Continuously monitor index bloat as bytes and percentage, alert if values exceed a set threshold. CentOS/RHEL/SL Configure a NTP Client And Server. check_postgres. Notes, comments? For timeseries, I got ~430MB (close to the 493MB from pg_relation_size) and 438MB for the TOAST table (using columns chunk_id, chunk_seq, chunk_data). PostgreSQL and bloat . Let’s say 9.3 to 11.6 on Centos Linux. of tuples to assume where bloat comes in. Re: [Wiki] Dead link in Index Maintenance page Hi Dimitri, A dead link to your old website has been pointed out to us. Heavily modified big table bloat even in auto vacuum is running. On Mon, Dec 19, 2016 at 6:15 AM, Kyotaro HORIGUCHI <[hidden email]> wrote: > Hello, recently one of my customer stumbled over an immoderate > catcache bloat. Mind that indexes are by default created with a fillfactor of 90, that is, index blocks are not filled to more than 90% by INSERT. It is designed to work with Nagios, MRTG, or in standalone scripts. Right now on your (8.1) system ANY update to a row is the equivalent of a delete/insert as far as the index is concerned, hence the index bloat. Check many things for a Postgres database, including connectivity, version, disk space used, table and index bloat, database size, relation size, locks, number of connections, transaction wraparound, and more. If the json values are large they'd > mostly be in … Pavel Monitor the bloat of indexes as both an absolute value (number of bytes) and as a percentage. ACL on Linux -- chacl examples. Documentation. It looks as if I have bloat, but not the traditional kind (unused bloat). To overcome this limitation, large field values are compressed and/or broken up into multiple physical rows. There are never updates or deletes, we just drop the partitions later. PostgreSQL uses a fixed page size (commonly 8 kB), and does not allow tuples to span multiple pages. Therefore, it is not possible to store very large field values directly. See the wiki for more info. This isn't only an issue for negative catcache entries. This is becoming a serious problem, as I've seen instances of these tables grow to 6 GB+ (on a 15 GB total database), while still effectively It requires pageinspect. Here are the top bloated tables before and after running a manual vacuum operation on all the tables in a heroku managed postgresql 9.2 database. The best advice I can give you in that regard is to upgrade to a newer version of Postgres (8.3 or later): This is when Postgres introduced Heap-Only Tuples support. This means that it displays which range of indexed values belong on each page, starting from the root. Playing with indexes and better bloat estimate. Most of the PostgreSQL DBAs might know about this large bloat estimate query integrated in check_postgres. This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. ACL on Linux -- getfacl examples. Will table bloat carry over to the new version. Indexes will have to be rebuilt when they become too bloated. Re: bloated postgres data folder, clean up at 2016-03-03 17:15:32 from Rémi Cura Responses Re: bloated postgres data folder, clean up at 2016-03-04 10:02:33 from Rémi Cura Once installed, you should be able to view the documentation locally by running: Postgres. The estimations look correct, and the TOAST table is WAY off the relation_size by about 2 orders of magnitude (60GB today). How To: Use check_postgres or pgmetrics to get bloat estimates. So I assume all table bloat will carry over to the new version. Some people misguidedly turn it down or off because they see it creating load; they should actually be turning it up in these situations. Apart of Postgres of them have gathered tens of gigabytes of data over the years indexes. A database this means that it displays which range of indexed values belong on each page, starting from root! 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