Re: Huge shared hit for small table - Mailing list pgsql-performance

From Peter Geoghegan
Subject Re: Huge shared hit for small table
Date
Msg-id CAH2-Wzm60__Ako=hy2-_5wsn==Sf+nC2-d2_Vt=TJSHKohOKbQ@mail.gmail.com
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In response to Re: Huge shared hit for small table  (Jeff Janes <jeff.janes@gmail.com>)
List pgsql-performance
On Mon, Nov 4, 2019 at 12:32 PM Jeff Janes <jeff.janes@gmail.com> wrote:
> Could there be a long-open transaction, which is preventing hint-bits from getting on set on the table rows, as well
onthe index rows? 

Contention on a small number of rows may also be a factor.

> A reindex would not by itself fix the problem if it were the long open transaction.  But  if the long open
transactionheld a sufficient lock on the table, then the reindex would block until the transaction went away on its
own,at which point the problem would go away on its own, so it might **appear** to have fixed the problem. 

That seems like the simplest and most likely explanation to me, even
though it isn't particularly simple.

--
Peter Geoghegan



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