Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
Skip to content

Commit d5dd3d4

Browse files
bmomjianbmomjian
committed
Add contrib/pg_freespacemap to display free space map information.
Mark Kirkwood
1 parent 6c0d4aa commit d5dd3d4

File tree

8 files changed

+481
-98
lines changed

8 files changed

+481
-98
lines changed

‎contrib/Makefile

+2-1
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
# $PostgreSQL: pgsql/contrib/Makefile,v 1.61 2005/09/01 22:02:44 tgl Exp $
1+
# $PostgreSQL: pgsql/contrib/Makefile,v 1.62 2006/02/12 03:55:52 momjian Exp $
22

33
subdir = contrib
44
top_builddir = ..
@@ -21,6 +21,7 @@ WANTED_DIRS = \
2121
ltree \
2222
oid2name \
2323
pg_buffercache \
24+
pg_freespacemap \
2425
pg_trgm \
2526
pgbench \
2627
pgcrypto \

‎contrib/README

+4
Original file line numberDiff line numberDiff line change
@@ -106,6 +106,10 @@ pg_buffercache -
106106
Real time queries on the shared buffer cache
107107
by Mark Kirkwood <markir@paradise.net.nz>
108108

109+
pg_freespacemap -
110+
Displays the contents of the free space map (FSM)
111+
by Mark Kirkwood <markir@paradise.net.nz>
112+
109113
pg_trgm -
110114
Functions for determining the similarity of text based on trigram
111115
matching.

‎contrib/pg_freespacemap/Makefile

+17
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,17 @@
1+
# $PostgreSQL: pgsql/contrib/pg_freespacemap/Makefile,v 1.1 2006/02/12 03:55:53 momjian Exp $
2+
3+
MODULE_big = pg_freespacemap
4+
OBJS = pg_freespacemap.o
5+
6+
DATA_built = pg_freespacemap.sql
7+
DOCS = README.pg_freespacemap
8+
9+
ifdef USE_PGXS
10+
PGXS := $(shell pg_config --pgxs)
11+
include $(PGXS)
12+
else
13+
subdir = contrib/pg_freespacemap
14+
top_builddir = ../..
15+
include $(top_builddir)/src/Makefile.global
16+
include $(top_srcdir)/contrib/contrib-global.mk
17+
endif

‎contrib/pg_freespacemap/README.pg_freespacemap

+98
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,98 @@
1+
Pg_freespacemap - Real time queries on the free space map (FSM).
2+
---------------
3+
4+
This module consists of a C function 'pg_freespacemap()' that returns
5+
a set of records, and a view 'pg_freespacemap' to wrapper the function.
6+
7+
The module provides the ability to examine the contents of the free space
8+
map, without having to restart or rebuild the server with additional
9+
debugging code.
10+
11+
By default public access is REVOKED from both of these, just in case there
12+
are security issues lurking.
13+
14+
15+
Installation
16+
------------
17+
18+
Build and install the main Postgresql source, then this contrib module:
19+
20+
$ cd contrib/pg_freespacemap
21+
$ gmake
22+
$ gmake install
23+
24+
25+
To register the functions:
26+
27+
$ psql -d <database> -f pg_freespacemap.sql
28+
29+
30+
Notes
31+
-----
32+
33+
The definition of the columns exposed in the view is:
34+
35+
Column | references | Description
36+
----------------+----------------------+------------------------------------
37+
blockid | | Id, 1.. max_fsm_pages
38+
relfilenode | pg_class.relfilenode | Refilenode of the relation.
39+
reltablespace | pg_tablespace.oid | Tablespace oid of the relation.
40+
reldatabase | pg_database.oid | Database for the relation.
41+
relblocknumber | | Offset of the page in the relation.
42+
blockfreebytes | | Free bytes in the block/page.
43+
44+
45+
There is one row for each page in the free space map.
46+
47+
Because the map is shared by all the databases, there are pages from
48+
relations not belonging to the current database.
49+
50+
When the pg_freespacemap view is accessed, internal free space map locks are
51+
taken, and a copy of the map data is made for the view to display.
52+
This ensures that the view produces a consistent set of results, while not
53+
blocking normal activity longer than necessary. Nonetheless there
54+
could be some impact on database performance if this view is read often.
55+
56+
57+
Sample output
58+
-------------
59+
60+
regression=# \d pg_freespacemap
61+
View "public.pg_freespacemap"
62+
Column | Type | Modifiers
63+
---------------+---------+-----------
64+
blockid | integer |
65+
relfilenode | oid |
66+
reltablespace | oid |
67+
reldatabase | oid |
68+
relblocknumber | bigint |
69+
blockfreebytes | integer |
70+
View definition:
71+
SELECT p.blockid, p.relfilenode, p.reltablespace, p.reldatabase, p.relblocknumber, p.blockfreebytes
72+
FROM pg_freespacemap() p(blockid integer, relfilenode oid, reltablespace oid, reldatabase oid, relblocknumber bigint, blockfreebytes integer);
73+
74+
regression=# SELECT c.relname, m.relblocknumber, m.blockfreebytes
75+
FROM pg_freespacemap m INNER JOIN pg_class c
76+
ON c.relfilenode = m.relfilenode LIMIT 10;
77+
relname | relblocknumber | blockfreebytes
78+
------------------------+----------------+----------------
79+
sql_features | 5 | 2696
80+
sql_implementation_info | 0 | 7104
81+
sql_languages | 0 | 8016
82+
sql_packages | 0 | 7376
83+
sql_sizing | 0 | 6032
84+
pg_authid | 0 | 7424
85+
pg_toast_2618 | 13 | 4588
86+
pg_toast_2618 | 12 | 1680
87+
pg_toast_2618 | 10 | 1436
88+
pg_toast_2618 | 7 | 1136
89+
(10 rows)
90+
91+
regression=#
92+
93+
94+
Author
95+
------
96+
97+
* Mark Kirkwood <markir@paradise.net.nz>
98+

‎contrib/pg_freespacemap/pg_freespacemap.c

+231
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,231 @@
1+
/*-------------------------------------------------------------------------
2+
*
3+
* pg_freespacemap.c
4+
* display some contents of the free space map.
5+
*
6+
* $PostgreSQL: pgsql/contrib/pg_freespacemap/pg_freespacemap.c,v 1.1 2006/02/12 03:55:53 momjian Exp $
7+
*-------------------------------------------------------------------------
8+
*/
9+
#include "postgres.h"
10+
#include "funcapi.h"
11+
#include "catalog/pg_type.h"
12+
#include "storage/freespace.h"
13+
#include "utils/relcache.h"
14+
15+
#define NUM_FREESPACE_PAGES_ELEM 6
16+
17+
#if defined(WIN32) || defined(__CYGWIN__)
18+
extern DLLIMPORT volatile uint32 InterruptHoldoffCount;
19+
#endif
20+
21+
Datum pg_freespacemap(PG_FUNCTION_ARGS);
22+
23+
24+
/*
25+
* Record structure holding the to be exposed free space data.
26+
*/
27+
typedef struct
28+
{
29+
30+
uint32 blockid;
31+
uint32 relfilenode;
32+
uint32 reltablespace;
33+
uint32 reldatabase;
34+
uint32 relblocknumber;
35+
uint32 blockfreebytes;
36+
37+
} FreeSpacePagesRec;
38+
39+
40+
/*
41+
* Function context for data persisting over repeated calls.
42+
*/
43+
typedef struct
44+
{
45+
46+
AttInMetadata *attinmeta;
47+
FreeSpacePagesRec *record;
48+
char *values[NUM_FREESPACE_PAGES_ELEM];
49+
50+
} FreeSpacePagesContext;
51+
52+
53+
/*
54+
* Function returning data from the Free Space Map (FSM).
55+
*/
56+
PG_FUNCTION_INFO_V1(pg_freespacemap);
57+
Datum
58+
pg_freespacemap(PG_FUNCTION_ARGS)
59+
{
60+
61+
FuncCallContext *funcctx;
62+
Datum result;
63+
MemoryContext oldcontext;
64+
FreeSpacePagesContext *fctx; /* User function context. */
65+
TupleDesc tupledesc;
66+
HeapTuple tuple;
67+
68+
FSMHeader *FreeSpaceMap; /* FSM main structure. */
69+
FSMRelation *fsmrel; /* Individual relation. */
70+
71+
72+
if (SRF_IS_FIRSTCALL())
73+
{
74+
uint32 i;
75+
uint32 numPages; /* Max possible no. of pages in map. */
76+
int nPages; /* Mapped pages for a relation. */
77+
78+
/*
79+
* Get the free space map data structure.
80+
*/
81+
FreeSpaceMap = GetFreeSpaceMap();
82+
83+
numPages = MaxFSMPages;
84+
85+
funcctx = SRF_FIRSTCALL_INIT();
86+
87+
/* Switch context when allocating stuff to be used in later calls */
88+
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
89+
90+
/* Construct a tuple to return. */
91+
tupledesc = CreateTemplateTupleDesc(NUM_FREESPACE_PAGES_ELEM, false);
92+
TupleDescInitEntry(tupledesc, (AttrNumber) 1, "blockid",
93+
INT4OID, -1, 0);
94+
TupleDescInitEntry(tupledesc, (AttrNumber) 2, "relfilenode",
95+
OIDOID, -1, 0);
96+
TupleDescInitEntry(tupledesc, (AttrNumber) 3, "reltablespace",
97+
OIDOID, -1, 0);
98+
TupleDescInitEntry(tupledesc, (AttrNumber) 4, "reldatabase",
99+
OIDOID, -1, 0);
100+
TupleDescInitEntry(tupledesc, (AttrNumber) 5, "relblocknumber",
101+
INT8OID, -1, 0);
102+
TupleDescInitEntry(tupledesc, (AttrNumber) 6, "blockfreebytes",
103+
INT4OID, -1, 0);
104+
105+
/* Generate attribute metadata needed later to produce tuples */
106+
funcctx->attinmeta = TupleDescGetAttInMetadata(tupledesc);
107+
108+
/*
109+
* Create a function context for cross-call persistence and initialize
110+
* the counters.
111+
*/
112+
fctx = (FreeSpacePagesContext *) palloc(sizeof(FreeSpacePagesContext));
113+
funcctx->user_fctx = fctx;
114+
115+
/* Set an upper bound on the calls */
116+
funcctx->max_calls = numPages;
117+
118+
119+
/* Allocate numPages worth of FreeSpacePagesRec records, this is also
120+
* an upper bound.
121+
*/
122+
fctx->record = (FreeSpacePagesRec *) palloc(sizeof(FreeSpacePagesRec) * numPages);
123+
124+
/* allocate the strings for tuple formation */
125+
fctx->values[0] = (char *) palloc(3 * sizeof(uint32) + 1);
126+
fctx->values[1] = (char *) palloc(3 * sizeof(uint32) + 1);
127+
fctx->values[2] = (char *) palloc(3 * sizeof(uint32) + 1);
128+
fctx->values[3] = (char *) palloc(3 * sizeof(uint32) + 1);
129+
fctx->values[4] = (char *) palloc(3 * sizeof(uint32) + 1);
130+
fctx->values[5] = (char *) palloc(3 * sizeof(uint32) + 1);
131+
132+
133+
/* Return to original context when allocating transient memory */
134+
MemoryContextSwitchTo(oldcontext);
135+
136+
137+
/*
138+
* Lock free space map and scan though all the relations,
139+
* for each relation, gets all its mapped pages.
140+
*/
141+
LWLockAcquire(FreeSpaceLock, LW_EXCLUSIVE);
142+
143+
144+
i = 0;
145+
146+
for (fsmrel = FreeSpaceMap->usageList; fsmrel; fsmrel = fsmrel->nextUsage)
147+
{
148+
149+
if (fsmrel->isIndex)
150+
{ /* Index relation. */
151+
IndexFSMPageData *page;
152+
153+
page = (IndexFSMPageData *)
154+
(FreeSpaceMap->arena + fsmrel->firstChunk * CHUNKBYTES);
155+
156+
for (nPages = 0; nPages < fsmrel->storedPages; nPages++)
157+
{
158+
159+
fctx->record[i].blockid = i;
160+
fctx->record[i].relfilenode = fsmrel->key.relNode;
161+
fctx->record[i].reltablespace = fsmrel->key.spcNode;
162+
fctx->record[i].reldatabase = fsmrel->key.dbNode;
163+
fctx->record[i].relblocknumber = IndexFSMPageGetPageNum(page);
164+
fctx->record[i].blockfreebytes = 0; /* index.*/
165+
166+
page++;
167+
i++;
168+
}
169+
}
170+
else
171+
{ /* Heap relation. */
172+
FSMPageData *page;
173+
174+
page = (FSMPageData *)
175+
(FreeSpaceMap->arena + fsmrel->firstChunk * CHUNKBYTES);
176+
177+
for (nPages = 0; nPages < fsmrel->storedPages; nPages++)
178+
{
179+
fctx->record[i].blockid = i;
180+
fctx->record[i].relfilenode = fsmrel->key.relNode;
181+
fctx->record[i].reltablespace = fsmrel->key.spcNode;
182+
fctx->record[i].reldatabase = fsmrel->key.dbNode;
183+
fctx->record[i].relblocknumber = FSMPageGetPageNum(page);
184+
fctx->record[i].blockfreebytes = FSMPageGetSpace(page);
185+
186+
page++;
187+
i++;
188+
}
189+
190+
}
191+
192+
}
193+
194+
/* Set the real no. of calls as we know it now! */
195+
funcctx->max_calls = i;
196+
197+
/* Release free space map. */
198+
LWLockRelease(FreeSpaceLock);
199+
}
200+
201+
funcctx = SRF_PERCALL_SETUP();
202+
203+
/* Get the saved state */
204+
fctx = funcctx->user_fctx;
205+
206+
207+
if (funcctx->call_cntr < funcctx->max_calls)
208+
{
209+
uint32 i = funcctx->call_cntr;
210+
211+
212+
sprintf(fctx->values[0], "%u", fctx->record[i].blockid);
213+
sprintf(fctx->values[1], "%u", fctx->record[i].relfilenode);
214+
sprintf(fctx->values[2], "%u", fctx->record[i].reltablespace);
215+
sprintf(fctx->values[3], "%u", fctx->record[i].reldatabase);
216+
sprintf(fctx->values[4], "%u", fctx->record[i].relblocknumber);
217+
sprintf(fctx->values[5], "%u", fctx->record[i].blockfreebytes);
218+
219+
220+
221+
/* Build and return the tuple. */
222+
tuple = BuildTupleFromCStrings(funcctx->attinmeta, fctx->values);
223+
result = HeapTupleGetDatum(tuple);
224+
225+
226+
SRF_RETURN_NEXT(funcctx, result);
227+
}
228+
else
229+
SRF_RETURN_DONE(funcctx);
230+
231+
}

‎contrib/pg_freespacemap/pg_freespacemap.sql.in

+19
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,19 @@
1+
-- Adjust this setting to control where the objects get created.
2+
BEGIN;
3+
SET search_path = public;
4+
5+
-- Register the function.
6+
CREATE OR REPLACE FUNCTION pg_freespacemap()
7+
RETURNS SETOF RECORD
8+
AS 'MODULE_PATHNAME', 'pg_freespacemap'
9+
LANGUAGE 'C';
10+
11+
-- Create a view for convenient access.
12+
CREATE VIEW pg_freespacemap AS
13+
SELECT P.* FROM pg_freespacemap() AS P
14+
(blockid int4, relfilenode oid, reltablespace oid, reldatabase oid, relblocknumber int8, blockfreebytes int4);
15+
16+
-- Don't want these to be available at public.
17+
REVOKE ALL ON FUNCTION pg_freespacemap() FROM PUBLIC;
18+
REVOKE ALL ON pg_freespacemap FROM PUBLIC;
19+
COMMIT;

0 commit comments

Comments
 (0)