doc: mention that INSERT can block because of unique indexes

Initial patch by David G. Johnston.

Reported-by: David G. Johnston

Discussion: https://postgr.es/m/CAKFQuwZpbdzceO41VE-xt1Xh8rWRRfgopTAK1wL9EhCo0Am-Sw@mail.gmail.com

Backpatch-through: 10
This commit is contained in:
Bruce Momjian 2022-07-14 15:17:19 -04:00
parent 3e071b2cf5
commit 6959e971b3
1 changed files with 5 additions and 0 deletions

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@ -75,6 +75,11 @@ INSERT INTO <replaceable class="parameter">table_name</replaceable> [ AS <replac
</para>
<para>
<command>INSERT</command> into tables that lack unique indexes will
not be blocked by concurrent activity. Tables with unique indexes
might block if concurrent sessions perform actions that lock or modify
rows matching the unique index values being inserted; the details
are covered in <xref linkend="index-unique-checks"/>.
<literal>ON CONFLICT</literal> can be used to specify an alternative
action to raising a unique constraint or exclusion constraint
violation error. (See <xref linkend="sql-on-conflict"/> below.)