Revise BuildIndexValueDescription to simplify it

Getting a pg_index tuple from syscache when the open index relation is
available is pointless -- just use the one from relcache.

Noticed while reviewing code for cb9db2ab0674.

No backpatch.

diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
index 58b44117961188c864e2792269df41b2a014e00c..9d08775687985313681bfc8b8bf5d9b5ef8b9a41 100644 (file)
--- a/src/backend/access/index/genam.c
+++ b/src/backend/access/index/genam.c
@@ -180,7 +180,6 @@ BuildIndexValueDescription(Relation indexRelation,
 {
        StringInfoData buf;
        Form_pg_index idxrec;
-       HeapTuple       ht_idx;
        int                     indnkeyatts;
        int                     i;
        int                     keyno;
@@ -200,24 +199,13 @@ BuildIndexValueDescription(Relation indexRelation,
         * Next we need to check table-level SELECT access and then, if there is
         * no access there, check column-level permissions.
         */
-
-       /*
-        * Fetch the pg_index tuple by the Oid of the index
-        */
-       ht_idx = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexrelid));
-       if (!HeapTupleIsValid(ht_idx))
-               elog(ERROR, "cache lookup failed for index %u", indexrelid);
-       idxrec = (Form_pg_index) GETSTRUCT(ht_idx);
-
+       idxrec = indexRelation->rd_index;
        indrelid = idxrec->indrelid;
        Assert(indexrelid == idxrec->indexrelid);
 
        /* RLS check- if RLS is enabled then we don't return anything. */
        if (check_enable_rls(indrelid, InvalidOid, true) == RLS_ENABLED)
-       {
-               ReleaseSysCache(ht_idx);
                return NULL;
-       }
 
        /* Table-level SELECT is enough, if the user has it */
        aclresult = pg_class_aclcheck(indrelid, GetUserId(), ACL_SELECT);
@@ -227,7 +215,7 @@ BuildIndexValueDescription(Relation indexRelation,
                 * No table-level access, so step through the columns in the index and
                 * make sure the user has SELECT rights on all of them.
                 */
-               for (keyno = 0; keyno < idxrec->indnkeyatts; keyno++)
+               for (keyno = 0; keyno < indnkeyatts; keyno++)
                {
                        AttrNumber      attnum = idxrec->indkey.values[keyno];
 
@@ -242,12 +230,10 @@ BuildIndexValueDescription(Relation indexRelation,
                                                                          ACL_SELECT) != ACLCHECK_OK)
                        {
                                /* No access, so clean up and return */
-                               ReleaseSysCache(ht_idx);
                                return NULL;
                        }
                }
        }
-       ReleaseSysCache(ht_idx);
 
        initStringInfo(&buf);
        appendStringInfo(&buf, "(%s)=(",