| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | depesz(at)depesz(dot)com |
| Cc: | Stephen Frost <sfrost(at)snowman(dot)net>, Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>, pgsql-general <pgsql-general(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Can we get rid of repeated queries from pg_dump? |
| Date: | 2021-08-28 22:26:21 |
| Message-ID: | 1082810.1630189581@sss.pgh.pa.us |
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| Lists: | pgsql-general pgsql-hackers |
Here is a second patch, quite independent of the first one, that
gets rid of some other repetitive queries. On the regression database,
the number of queries needed to do "pg_dump -s regression" drops from
3260 to 2589, and on my machine it takes 1.8 sec instead of 2.1 sec.
What's attacked here is a fairly silly decision in getPolicies()
to query pg_policy once per table, when we could do so just once.
It might have been okay if we skipped the per-table query for
tables that lack policies, but it's not clear to me that we can
know that without looking into pg_policy. In any case I doubt
this is ever going to be less efficient than the original coding.
regards, tom lane
| Attachment | Content-Type | Size |
|---|---|---|
| query-pg_policy-just-once.patch | text/x-diff | 5.4 KB |
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