Adjust /contrib/pg_freespace to show index free space as NULL (FSM only

tracks index pages, not free space on pages):

1/ Index free bytes set to NULL
2/ Comment added to the README briefly mentioning the index business
3/ Columns reordered more logically
4/ 'Blockid' column removed
5/ Free bytes column renamed to just 'bytes' instead of 'blockfreebytes'

Mark Kirkwood

diff --git a/contrib/pg_freespacemap/README.pg_freespacemap b/contrib/pg_freespacemap/README.pg_freespacemap
index d1711254c4f6f6c8d0b28b046b4e8c35862a2b53..8657acc27b87d81b035bcf53189fe0f8500fa819 100644 (file)
--- a/contrib/pg_freespacemap/README.pg_freespacemap
+++ b/contrib/pg_freespacemap/README.pg_freespacemap
@@ -34,12 +34,12 @@ Notes
 
        Column     |  references          | Description
   ----------------+----------------------+------------------------------------
-   blockid        |                      | Id, 1.. max_fsm_pages
-   relfilenode    | pg_class.relfilenode | Refilenode of the relation.
    reltablespace  | pg_tablespace.oid    | Tablespace oid of the relation.
    reldatabase    | pg_database.oid      | Database for the relation.
+   relfilenode    | pg_class.relfilenode | Refilenode of the relation.
    relblocknumber |                      | Offset of the page in the relation.
-   blockfreebytes |                      | Free bytes in the block/page.
+   bytes          |                      | Free bytes in the block/page, or NULL
+                  |                      | for an index page (see below).
 
 
   There is one row for each page in the free space map.
@@ -47,6 +47,9 @@ Notes
   Because the map is shared by all the databases, there are pages from
   relations not belonging to the current database.
 
+  The free space map can contain pages for btree indexes if they were emptied 
+  by a vacuum process. The bytes field is set to NULL in this case.
+
   When the pg_freespacemap view is accessed, internal free space map locks are
   taken, and a copy of the map data is made for the view to display. 
   This ensures that the view produces a consistent set of results, while not 
@@ -58,34 +61,33 @@ Sample output
 -------------
 
   regression=# \d pg_freespacemap
-      View "public.pg_freespacemap"
+     View "public.pg_freespacemap"
       Column     |  Type   | Modifiers 
-  ---------------+---------+-----------
-  blockid        | integer | 
-  relfilenode    | oid     | 
+ ----------------+---------+-----------
   reltablespace  | oid     | 
   reldatabase    | oid     | 
+  relfilenode    | oid     | 
   relblocknumber | bigint  | 
-  blockfreebytes | integer | 
+  bytes          | integer | 
  View definition:
-  SELECT p.blockid, p.relfilenode, p.reltablespace, p.reldatabase, p.relblocknumber, p.blockfreebytes
-    FROM pg_freespacemap() p(blockid integer, relfilenode oid, reltablespace oid, reldatabase oid, relblocknumber bigint, blockfreebytes integer);
+ SELECT p.reltablespace, p.reldatabase, p.relfilenode, p.relblocknumber, p.bytes
+ FROM pg_freespacemap() p(reltablespace oid, reldatabase oid, relfilenode oid, relblocknumber bigint, bytes integer);
 
-  regression=# SELECT c.relname, m.relblocknumber, m.blockfreebytes  
+  regression=# SELECT c.relname, m.relblocknumber, m.bytes  
                FROM pg_freespacemap m INNER JOIN pg_class c 
                ON c.relfilenode = m.relfilenode LIMIT 10;
-      relname             | relblocknumber | blockfreebytes 
-  ------------------------+----------------+----------------
-  sql_features            |              5 |           2696
-  sql_implementation_info |              0 |           7104
-  sql_languages           |              0 |           8016
-  sql_packages            |              0 |           7376
-  sql_sizing              |              0 |           6032
-  pg_authid               |              0 |           7424
-  pg_toast_2618           |             13 |           4588
-  pg_toast_2618           |             12 |           1680
-  pg_toast_2618           |             10 |           1436
-  pg_toast_2618           |              7 |           1136
+      relname             | relblocknumber |  bytes 
+  ------------------------+----------------+--------
+  sql_features            |              5 |   2696
+  sql_implementation_info |              0 |   7104
+  sql_languages           |              0 |   8016
+  sql_packages            |              0 |   7376
+  sql_sizing              |              0 |   6032
+  pg_authid               |              0 |   7424
+  pg_toast_2618           |             13 |   4588
+  pg_toast_2618           |             12 |   1680
+  pg_toast_2618           |             10 |   1436
+  pg_toast_2618           |              7 |   1136
   (10 rows)
 
   regression=# 

diff --git a/contrib/pg_freespacemap/pg_freespacemap.c b/contrib/pg_freespacemap/pg_freespacemap.c
index 471c97a100be60b260629507d29e794488ab4463..7225be242c466b28cdcd121a52e5f259df51136c 100644 (file)
--- a/contrib/pg_freespacemap/pg_freespacemap.c
+++ b/contrib/pg_freespacemap/pg_freespacemap.c
@@ -3,7 +3,7 @@
  * pg_freespacemap.c
  *   display some contents of the free space map.
  *
- *   $PostgreSQL: pgsql/contrib/pg_freespacemap/pg_freespacemap.c,v 1.2 2006/02/14 15:03:59 tgl Exp $
+ *   $PostgreSQL: pgsql/contrib/pg_freespacemap/pg_freespacemap.c,v 1.3 2006/04/26 22:41:18 momjian Exp $
  *-------------------------------------------------------------------------
  */
 #include "postgres.h"
@@ -12,7 +12,7 @@
 #include "storage/freespace.h"
 #include "utils/relcache.h"
 
-#define        NUM_FREESPACE_PAGES_ELEM    6
+#define        NUM_FREESPACE_PAGES_ELEM    5
 
 #if defined(WIN32) || defined(__CYGWIN__)
 /* Need DLLIMPORT for some things that are not so marked in main headers */
@@ -29,12 +29,12 @@ Datum       pg_freespacemap(PG_FUNCTION_ARGS);
 typedef struct
 {
 
-   uint32              blockid;
-   uint32              relfilenode;
    uint32              reltablespace;
    uint32              reldatabase;
+   uint32              relfilenode;
    uint32              relblocknumber;
-   uint32              blockfreebytes;
+   uint32              bytes;
+   bool                isindex;
 
 }  FreeSpacePagesRec;
 
@@ -91,17 +91,15 @@ pg_freespacemap(PG_FUNCTION_ARGS)
 
        /* Construct a tuple to return. */
        tupledesc = CreateTemplateTupleDesc(NUM_FREESPACE_PAGES_ELEM, false);
-       TupleDescInitEntry(tupledesc, (AttrNumber) 1, "blockid",
-                          INT4OID, -1, 0);
-       TupleDescInitEntry(tupledesc, (AttrNumber) 2, "relfilenode",
+       TupleDescInitEntry(tupledesc, (AttrNumber) 1, "reltablespace",
                           OIDOID, -1, 0);
-       TupleDescInitEntry(tupledesc, (AttrNumber) 3, "reltablespace",
+       TupleDescInitEntry(tupledesc, (AttrNumber) 2, "reldatabase",
                           OIDOID, -1, 0);
-       TupleDescInitEntry(tupledesc, (AttrNumber) 4, "reldatabase",
+       TupleDescInitEntry(tupledesc, (AttrNumber) 3, "relfilenode",
                           OIDOID, -1, 0);
-       TupleDescInitEntry(tupledesc, (AttrNumber) 5, "relblocknumber",
+       TupleDescInitEntry(tupledesc, (AttrNumber) 4, "relblocknumber",
                           INT8OID, -1, 0);
-       TupleDescInitEntry(tupledesc, (AttrNumber) 6, "blockfreebytes",
+       TupleDescInitEntry(tupledesc, (AttrNumber) 5, "bytes",
                           INT4OID, -1, 0);
 
        /* Generate attribute metadata needed later to produce tuples */
@@ -129,7 +127,6 @@ pg_freespacemap(PG_FUNCTION_ARGS)
        fctx->values[2] = (char *) palloc(3 * sizeof(uint32) + 1);
        fctx->values[3] = (char *) palloc(3 * sizeof(uint32) + 1);
        fctx->values[4] = (char *) palloc(3 * sizeof(uint32) + 1);
-       fctx->values[5] = (char *) palloc(3 * sizeof(uint32) + 1);
 
 
        /* Return to original context when allocating transient memory */
@@ -158,12 +155,12 @@ pg_freespacemap(PG_FUNCTION_ARGS)
                for (nPages = 0; nPages < fsmrel->storedPages; nPages++)
                {
 
-                   fctx->record[i].blockid = i;
-                   fctx->record[i].relfilenode = fsmrel->key.relNode;
                    fctx->record[i].reltablespace = fsmrel->key.spcNode;
                    fctx->record[i].reldatabase = fsmrel->key.dbNode;
+                   fctx->record[i].relfilenode = fsmrel->key.relNode;
                    fctx->record[i].relblocknumber = IndexFSMPageGetPageNum(page);  
-                   fctx->record[i].blockfreebytes = 0; /* index.*/
+                   fctx->record[i].bytes = 0;  
+                   fctx->record[i].isindex = true; 
 
                    page++;
                    i++;
@@ -178,12 +175,12 @@ pg_freespacemap(PG_FUNCTION_ARGS)
 
                for (nPages = 0; nPages < fsmrel->storedPages; nPages++)
                {
-                   fctx->record[i].blockid = i;
-                   fctx->record[i].relfilenode = fsmrel->key.relNode;
                    fctx->record[i].reltablespace = fsmrel->key.spcNode;
                    fctx->record[i].reldatabase = fsmrel->key.dbNode;
+                   fctx->record[i].relfilenode = fsmrel->key.relNode;
                    fctx->record[i].relblocknumber = FSMPageGetPageNum(page);
-                   fctx->record[i].blockfreebytes = FSMPageGetSpace(page); 
+                   fctx->record[i].bytes = FSMPageGetSpace(page);  
+                   fctx->record[i].isindex = false;    
                    
                    page++;
                    i++;
@@ -209,19 +206,41 @@ pg_freespacemap(PG_FUNCTION_ARGS)
    if (funcctx->call_cntr < funcctx->max_calls)
    {
        uint32      i = funcctx->call_cntr;
+       char        *values[NUM_FREESPACE_PAGES_ELEM];
+       int         j;
 
+       /*
+        * Use a temporary values array, initially pointing to fctx->values,
+        * so it can be reassigned w/o losing the storage for subsequent
+        * calls.
+        */
+       for (j = 0; j < NUM_FREESPACE_PAGES_ELEM; j++)
+       {
+           values[j] = fctx->values[j];
+       }
+
+
+       sprintf(values[0], "%u", fctx->record[i].reltablespace);
+       sprintf(values[1], "%u", fctx->record[i].reldatabase);
+       sprintf(values[2], "%u", fctx->record[i].relfilenode);
+       sprintf(values[3], "%u", fctx->record[i].relblocknumber);
 
-       sprintf(fctx->values[0], "%u", fctx->record[i].blockid);
-       sprintf(fctx->values[1], "%u", fctx->record[i].relfilenode);
-       sprintf(fctx->values[2], "%u", fctx->record[i].reltablespace);
-       sprintf(fctx->values[3], "%u", fctx->record[i].reldatabase);
-       sprintf(fctx->values[4], "%u", fctx->record[i].relblocknumber);
-       sprintf(fctx->values[5], "%u", fctx->record[i].blockfreebytes);
 
+       /*
+        * Set (free) bytes to NULL for an index relation.
+        */
+       if (fctx->record[i].isindex == true)
+       {
+           values[4] = NULL;
+       }
+       else
+       {
+           sprintf(values[4], "%u", fctx->record[i].bytes);
+       }
 
 
        /* Build and return the tuple. */
-       tuple = BuildTupleFromCStrings(funcctx->attinmeta, fctx->values);
+       tuple = BuildTupleFromCStrings(funcctx->attinmeta, values);
        result = HeapTupleGetDatum(tuple);
 
 

diff --git a/contrib/pg_freespacemap/pg_freespacemap.sql.in b/contrib/pg_freespacemap/pg_freespacemap.sql.in
index 26574ea1c09c39c1f628de494682a832c14d8884..b69026953f5e1fcc67f9b384857f50de9d5ed1e9 100644 (file)
--- a/contrib/pg_freespacemap/pg_freespacemap.sql.in
+++ b/contrib/pg_freespacemap/pg_freespacemap.sql.in
@@ -11,7 +11,7 @@ LANGUAGE C;
 -- Create a view for convenient access.
 CREATE VIEW pg_freespacemap AS
    SELECT P.* FROM pg_freespacemap() AS P
-   (blockid int4, relfilenode oid, reltablespace oid, reldatabase oid, relblocknumber int8, blockfreebytes int4);
+   (reltablespace oid, reldatabase oid, relfilenode oid, relblocknumber int8, bytes int4);
  
 -- Don't want these to be available at public.
 REVOKE ALL ON FUNCTION pg_freespacemap() FROM PUBLIC;