Fix pg_dump --clean with partitioned indexes.

We'd try to drop the partitions of a partitioned index separately,
which is disallowed by the backend, leading to an error during
restore.  While the error is harmless, it causes problems if you
try to use --single-transaction mode.

Fortunately, there seems no need to do a DROP at all, since the
partition will go away silently when we drop either the parent index
or the partition's table.  So just make the DROP conditional on not
being a partition.

Reported-by: jian he <jian.universality@gmail.com>
Author: jian he <jian.universality@gmail.com>
Reviewed-by: Pavel Stehule <pavel.stehule@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CACJufxF0QSdkjFKF4di-JGWN6CSdQYEAhGPmQJJCdkSZtd=oLg@mail.gmail.com
Backpatch-through: 13

diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 4c098f20ad3e4a66cf9e262e2212d47c0a9ea891..ea5b020325b33277d05ccf729f0f3a6037814e13 100644 (file)
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -17015,7 +17015,17 @@ dumpIndex(Archive *fout, IndxInfo *indxinfo)
                              qindxname);
        }
 
-       appendPQExpBuffer(delq, "DROP INDEX %s;\n", qqindxname);
+       /*
+        * If this index is a member of a partitioned index, the backend will
+        * not allow us to drop it separately, so don't try.  It will go away
+        * automatically when we drop either the index's table or the
+        * partitioned index.  (If, in a selective restore with --clean, we
+        * drop neither of those, then this index will not be dropped either.
+        * But that's fine, and even if you think it's not, the backend won't
+        * let us do differently.)
+        */
+       if (indxinfo->parentidx == 0)
+           appendPQExpBuffer(delq, "DROP INDEX %s;\n", qqindxname);
 
        if (indxinfo->dobj.dump & DUMP_COMPONENT_DEFINITION)
            ArchiveEntry(fout, indxinfo->dobj.catId, indxinfo->dobj.dumpId,
@@ -17069,11 +17079,15 @@ dumpIndexAttach(Archive *fout, IndexAttachInfo *attachinfo)
                          fmtQualifiedDumpable(attachinfo->partitionIdx));
 
        /*
-        * There is no point in creating a drop query as the drop is done by
-        * index drop.  (If you think to change this, see also
-        * _printTocEntry().)  Although this object doesn't really have
-        * ownership as such, set the owner field anyway to ensure that the
-        * command is run by the correct role at restore time.
+        * There is no need for a dropStmt since the drop is done implicitly
+        * when we drop either the index's table or the partitioned index.
+        * Moreover, since there's no ALTER INDEX DETACH PARTITION command,
+        * there's no way to do it anyway.  (If you think to change this,
+        * consider also what to do with --if-exists.)
+        *
+        * Although this object doesn't really have ownership as such, set the
+        * owner field anyway to ensure that the command is run by the correct
+        * role at restore time.
         */
        ArchiveEntry(fout, attachinfo->dobj.catId, attachinfo->dobj.dumpId,
                     ARCHIVE_OPTS(.tag = attachinfo->dobj.name,