Re: Slow Bitmap Index Scan
От | Scott Rankin |
---|---|
Тема | Re: Slow Bitmap Index Scan |
Дата | |
Msg-id | EE225117-33A4-45E7-9D41-680D591AC5C9@motus.com обсуждение исходный текст |
Ответ на | Re: Slow Bitmap Index Scan (Justin Pryzby <pryzby@telsasoft.com>) |
Ответы |
Re: Slow Bitmap Index Scan
(Alan Hodgson <ahodgson@lists.simkin.ca>)
|
Список | pgsql-performance |
Upon further analysis, this is - unsurprisingly - taking place when we have multiple prefixed search terms in a ts_querygoing against a tsvector index. We have roughly 30 million rows in the table, and the search column is basically a concatenation of a location's name (think"Walmart #123456") and its street address. We use these searches mostly for autocompleting of a location search. So the search for that record above might be "Walmart123", which we change to be to_tsquery('walmart:* &123:*'). We prefix both terms to correct for misspellings orlazy typing. Is it unrealistic to think that we could have sub-1000ms searches against that size of a table? On 11/28/18, 2:18 PM, "Justin Pryzby" <pryzby@telsasoft.com> wrote: On Wed, Nov 28, 2018 at 07:08:53PM +0000, Scott Rankin wrote: > We recently moved our production database systems from a 9.4 running on a self-managed EC2 instance to 9.6.10 on Amazon’sAWS (same RAM, CPU). After the move, we’re finding that certain queries that we run against a GIN full-text indexhave some occasionally very slow executions and I’m struggling to figure out what to do about it. I would be verygrateful for any ideas! > > The setup we have is a 32-core, 244 GB RAM primary with a same-sized read replica. The queries are running off thereplica, but performance is roughly the same between the master and the replica. > > Here’s a query that’s performing badly: Can you compare or show the explain(analyze,buffers) for a fast query instance vs slow query instance ? Is it slower due to index access or heap? Due to cache misses ? Also, you have big ram - have you tried disabling KSM or THP ? https://www.postgresql.org/message-id/20170718180152.GE17566%40telsasoft.com Justin This email message contains information that Motus, LLC considers confidential and/or proprietary, or may later designateas confidential and proprietary. It is intended only for use of the individual or entity named above and shouldnot be forwarded to any other persons or entities without the express consent of Motus, LLC, nor should it be usedfor any purpose other than in the course of any potential or actual business relationship with Motus, LLC. If the readerof this message is not the intended recipient, or the employee or agent responsible to deliver it to the intended recipient,you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited.If you have received this communication in error, please notify sender immediately and destroy the original message. Internal Revenue Service regulations require that certain types of written advice include a disclaimer. To the extent thepreceding message contains advice relating to a Federal tax issue, unless expressly stated otherwise the advice is notintended or written to be used, and it cannot be used by the recipient or any other taxpayer, for the purpose of avoidingFederal tax penalties, and was not written to support the promotion or marketing of any transaction or matter discussedherein.
В списке pgsql-performance по дате отправления:
Предыдущее
От: Pavel StehuleДата:
Сообщение: Re: Query with high planning time at version 11.1 compared versions10.5 and 11.0