On 2020-05-14 03:07, Michael Paquier wrote:
On Wed, May 13, 2020 at 05:17:43PM +0300, Marina Polyakova wrote:
in my opinion it's a little unclear what "or default" means at the
end,
because the comma is used to separate enumeration elements ("d =
default
<...>, n = nothing, f = all columns, i = index <...>") and inside the
element description ("i = index with indisreplident set, or default").
Therefore here is an additional patch from me to clarify this place,
thanks
to Alexander Lakhin for help.
Yes, I agree that this last "or default" in the docs does not make
much sense, because we always enforce REPLICA_IDENTITY_NOTHING if
there is no replica identity.
This looks like a shortened version of a comment from
src/include/catalog/pg_class.h:
/*
* an explicitly chosen candidate key's columns are used as replica
identity.
* Note this will still be set if the index has been dropped; in that
case it
* has the same meaning as 'd'.
*/
#define REPLICA_IDENTITY_INDEX 'i'
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index
02ddebae99d98110a8dd290dd4cb0c980adf7984..034a08f80ea4269f131e7e1383ba482fd76d9344
100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -1936,7 +1936,7 @@ SCRAM-SHA-256$<replaceable><iteration
count></replaceable>:<replaceable>&l
<literal>d</literal> = default (primary key, if any),
<literal>n</literal> = nothing,
<literal>f</literal> = all columns,
- <literal>i</literal> = index with
<structfield>indisreplident</structfield> set, or default
+ <literal>i</literal> = index with
<structfield>indisreplident</structfield> set (if any)
</entry>
</row>
And you don't need the ("if any") either here, no?
REPLICA_IDENTITY_INDEX means that we have an index associated with the
replica identity so it seems to me that this last part can just be
removed.
I tried to save information for cases when the index is dropped as in
the code comment (see above) and the function RelationGetIndexList
(where IIUC we check if this index exists):
if (replident == REPLICA_IDENTITY_DEFAULT && OidIsValid(pkeyIndex))
relation->rd_replidindex = pkeyIndex;
else if (replident == REPLICA_IDENTITY_INDEX &&
OidIsValid(candidateIndex))
relation->rd_replidindex = candidateIndex;
else
relation->rd_replidindex = InvalidOid;
Perhaps it will be useful for some users to know that relreplident = i
does not mean that the required index exists (as in default case)?..
--
Marina Polyakova
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
