Fix temporary tablespaces for shared filesets some more.

Commit ecd9e9f0b fixed the problem in the wrong place, causing unwanted
side-effects on the behavior of GetNextTempTableSpace().  Instead,
let's make SharedFileSetInit() responsible for subbing in the value
of MyDatabaseTableSpace when the default tablespace is called for.

The convention about what is in the tempTableSpaces[] array is
evidently insufficiently documented, so try to improve that.

It also looks like SharedFileSetInit() is doing the wrong thing in the
case where temp_tablespaces is empty.  It was hard-wiring use of the
pg_default tablespace, but it seems like using MyDatabaseTableSpace
is more consistent with what happens for other temp files.

Back-patch the reversion of PrepareTempTablespaces()'s behavior to
9.5, as ecd9e9f0b was.  The changes in SharedFileSetInit() go back
to v11 where that was introduced.  (Note there is net zero code change
before v11 from these two patch sets, so nothing to release-note.)

Magnus Hagander and Tom Lane

Discussion: https://postgr.es/m/CABUevExg5YEsOvqMxrjoNvb3ApVyH+9jggWGKwTDFyFCVWczGQ@mail.gmail.com

diff --git a/src/backend/commands/tablespace.c b/src/backend/commands/tablespace.c
index f887ee98577b081400af0bb355b673514add61e0..2c3b9050b278763891854ee0842baafd00cfe19a 100644 (file)
--- a/src/backend/commands/tablespace.c
+++ b/src/backend/commands/tablespace.c
@@ -1183,6 +1183,7 @@ GetDefaultTablespace(char relpersistence, bool partitioned)
 
 typedef struct
 {
+   /* Array of OIDs to be passed to SetTempTablespaces() */
    int         numSpcs;
    Oid         tblSpcs[FLEXIBLE_ARRAY_MEMBER];
 } temp_tablespaces_extra;
@@ -1232,6 +1233,7 @@ check_temp_tablespaces(char **newval, void **extra, GucSource source)
            /* Allow an empty string (signifying database default) */
            if (curname[0] == '\0')
            {
+               /* InvalidOid signifies database's default tablespace */
                tblSpcs[numSpcs++] = InvalidOid;
                continue;
            }
@@ -1258,6 +1260,7 @@ check_temp_tablespaces(char **newval, void **extra, GucSource source)
             */
            if (curoid == MyDatabaseTableSpace)
            {
+               /* InvalidOid signifies database's default tablespace */
                tblSpcs[numSpcs++] = InvalidOid;
                continue;
            }
@@ -1368,6 +1371,7 @@ PrepareTempTablespaces(void)
        /* Allow an empty string (signifying database default) */
        if (curname[0] == '\0')
        {
+           /* InvalidOid signifies database's default tablespace */
            tblSpcs[numSpcs++] = InvalidOid;
            continue;
        }
@@ -1386,7 +1390,8 @@ PrepareTempTablespaces(void)
         */
        if (curoid == MyDatabaseTableSpace)
        {
-           tblSpcs[numSpcs++] = curoid;
+           /* InvalidOid signifies database's default tablespace */
+           tblSpcs[numSpcs++] = InvalidOid;
            continue;
        }
 

diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index 7dc6dd2f1593167a05e368a7ca487707e620e5e8..5f6420efb2d76e76fbfee6c00b6080981e9e80f4 100644 (file)
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -264,8 +264,10 @@ static int numExternalFDs = 0;
 static long tempFileCounter = 0;
 
 /*
- * Array of OIDs of temp tablespaces.  When numTempTableSpaces is -1,
- * this has not been set in the current transaction.
+ * Array of OIDs of temp tablespaces.  (Some entries may be InvalidOid,
+ * indicating that the current database's default tablespace should be used.)
+ * When numTempTableSpaces is -1, this has not been set in the current
+ * transaction.
  */
 static Oid *tempTableSpaces = NULL;
 static int numTempTableSpaces = -1;
@@ -2779,6 +2781,9 @@ closeAllVfds(void)
  * unless this function is called again before then.  It is caller's
  * responsibility that the passed-in array has adequate lifespan (typically
  * it'd be allocated in TopTransactionContext).
+ *
+ * Some entries of the array may be InvalidOid, indicating that the current
+ * database's default tablespace should be used.
  */
 void
 SetTempTablespaces(Oid *tableSpaces, int numSpaces)
@@ -2818,7 +2823,10 @@ TempTablespacesAreSet(void)
  * GetTempTablespaces
  *
  * Populate an array with the OIDs of the tablespaces that should be used for
- * temporary files.  Return the number that were copied into the output array.
+ * temporary files.  (Some entries may be InvalidOid, indicating that the
+ * current database's default tablespace should be used.)  At most numSpaces
+ * entries will be filled.
+ * Returns the number of OIDs that were copied into the output array.
  */
 int
 GetTempTablespaces(Oid *tableSpaces, int numSpaces)

diff --git a/src/backend/storage/file/sharedfileset.c b/src/backend/storage/file/sharedfileset.c
index f7206c9175f38d1c4ed2eeafd7462c7fa5276ee0..16b7594756c6661cb7d276ce6e2d3737ebe0eb25 100644 (file)
--- a/src/backend/storage/file/sharedfileset.c
+++ b/src/backend/storage/file/sharedfileset.c
@@ -63,9 +63,25 @@ SharedFileSetInit(SharedFileSet *fileset, dsm_segment *seg)
                           lengthof(fileset->tablespaces));
    if (fileset->ntablespaces == 0)
    {
-       fileset->tablespaces[0] = DEFAULTTABLESPACE_OID;
+       /* If the GUC is empty, use current database's default tablespace */
+       fileset->tablespaces[0] = MyDatabaseTableSpace;
        fileset->ntablespaces = 1;
    }
+   else
+   {
+       int         i;
+
+       /*
+        * An entry of InvalidOid means use the default tablespace for the
+        * current database.  Replace that now, to be sure that all users of
+        * the SharedFileSet agree on what to do.
+        */
+       for (i = 0; i < fileset->ntablespaces; i++)
+       {
+           if (fileset->tablespaces[i] == InvalidOid)
+               fileset->tablespaces[i] = MyDatabaseTableSpace;
+       }
+   }
 
    /* Register our cleanup callback. */
    on_dsm_detach(seg, SharedFileSetOnDetach, PointerGetDatum(fileset));