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hash: Increase the number of possible overflow bitmaps by 8x.

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Per a report from AP, it's not that hard to exhaust the supply of
bitmap pages if you create a table with a hash index and then insert a
few billion rows - and then you start getting errors when you try to
insert additional rows.  In the particular case reported by AP,
there's another fix that we can make to improve recycling of overflow
pages, which is another way to avoid the error, but there may be other
cases where this problem happens and that fix won't help.  So let's
buy ourselves as much headroom as we can without rearchitecting
anything.

The comments claim that the old limit was 64GB, but it was really
only 32GB, because we didn't use all the bits in the page for bitmap
bits - only the largest power of 2 that could fit after deducting
space for the page header and so forth.  Thus, we have 4kB per page
for bitmap bits, not 8kB.  The new limit is thus actually 8 times the
old *real* limit but only 4 times the old *purported* limit.

Since this breaks on-disk compatibility, bump HASH_VERSION.  We've
already done this earlier in this release cycle, so this doesn't cause
any incremental inconvenience for people using pg_upgrade from
releases prior to v10.  However, users who use pg_upgrade to reach
10beta3 or later from 10beta2 or earlier will need to REINDEX any hash
indexes again.

Amit Kapila and Robert Haas

Discussion: http://postgr.es/m/20170704105728.mwb72jebfmok2nm2@zip.com.au
This commit is contained in:
Robert Haas 2017-08-04 15:29:26 -04:00
parent c30f1770a9
commit 620b49a16d
5 changed files with 19 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
contrib/pageinspect/expected/hash.out
View File

@ -43,9 +43,9 @@ ERROR: invalid overflow block number 5
SELECT magic, version, ntuples, bsize, bmsize, bmshift, maxbucket, highmask,
lowmask, ovflpoint, firstfree, nmaps, procid, spares, mapp FROM
hash_metapage_info(get_raw_page('test_hash_a_idx', 0));
-[ RECORD 1 ]----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-[ RECORD 1 ]--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
magic | 105121344
version | 3
version | 4
ntuples | 1
bsize | 8152
bmsize | 4096
@ -58,7 +58,7 @@ firstfree | 0
nmaps | 1
procid | 450
spares | {0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
mapp | {5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
mapp | {5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
SELECT magic, version, ntuples, bsize, bmsize, bmshift, maxbucket, highmask,
lowmask, ovflpoint, firstfree, nmaps, procid, spares, mapp FROM

4
contrib/pgstattuple/expected/pgstattuple.out
View File

@ -134,7 +134,7 @@ create index test_hashidx on test using hash (b);
select * from pgstathashindex('test_hashidx');
version | bucket_pages | overflow_pages | bitmap_pages | unused_pages | live_items | dead_items | free_percent
---------+--------------+----------------+--------------+--------------+------------+------------+--------------
3 | 4 | 0 | 1 | 0 | 0 | 0 | 100
4 | 4 | 0 | 1 | 0 | 0 | 0 | 100
(1 row)
-- these should error with the wrong type
@ -235,7 +235,7 @@ select pgstatindex('test_partition_idx');
select pgstathashindex('test_partition_hash_idx');
pgstathashindex
---------------------
(3,8,0,1,0,0,0,100)
(4,8,0,1,0,0,0,100)
(1 row)
drop table test_partitioned;

13
doc/src/sgml/pageinspect.sgml
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@ -687,8 +687,13 @@ test=# SELECT * FROM hash_bitmap_info('con_hash_index', 2052);
<function>hash_metapage_info</function> returns information stored
in meta page of a <acronym>HASH</acronym> index. For example:
<screen>
test=# SELECT * FROM hash_metapage_info(get_raw_page('con_hash_index', 0));
-[ RECORD 1 ]-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
test=# SELECT magic, version, ntuples, ffactor, bsize, bmsize, bmshift,
test-# maxbucket, highmask, lowmask, ovflpoint, firstfree, nmaps, procid,
test-# regexp_replace(spares::text, '(,0)*}', '}') as spares,
test-# regexp_replace(mapp::text, '(,0)*}', '}') as mapp
test-# FROM hash_metapage_info(get_raw_page('con_hash_index', 0));
-[ RECORD 1 ]-------------------------------------------------------------------------------
spares | {0,0,0,0,0,0,1,1,1,1,1,1,1,1,3,4,4,4,45,55,58,59,508,567,628,704,1193,1202,1204}
magic | 105121344
version | 3
ntuples | 500500
@ -703,8 +708,8 @@ ovflpoint | 28
firstfree | 1204
nmaps | 1
procid | 450
spares | {0,0,0,0,0,0,1,1,1,1,1,1,1,1,3,4,4,4,45,55,58,59,508,567,628,704,1193,1202,1204,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
mapp | {65,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
spares | {0,0,0,0,0,0,1,1,1,1,1,1,1,1,3,4,4,4,45,55,58,59,508,567,628,704,1193,1202,1204}
mapp | {65}
</screen>
</para>
</listitem>

2
doc/src/sgml/pgstattuple.sgml
View File

@ -368,7 +368,7 @@ pending_tuples | 0
<programlisting>
test=&gt; select * from pgstathashindex('con_hash_index');
-[ RECORD 1 ]--+-----------------
version | 2
version | 4
bucket_pages | 33081
overflow_pages | 0
bitmap_pages | 1

9
src/include/access/hash.h
View File

@ -158,8 +158,7 @@ typedef HashScanOpaqueData *HashScanOpaque;
#define HASH_METAPAGE 0 /* metapage is always block 0 */
#define HASH_MAGIC 0x6440640
#define HASH_VERSION 3 /* 3 signifies multi-phased bucket allocation
* to reduce doubling */
#define HASH_VERSION 4
/*
* spares[] holds the number of overflow pages currently allocated at or
@ -182,10 +181,10 @@ typedef HashScanOpaqueData *HashScanOpaque;
* after HASH_SPLITPOINT_GROUPS_WITH_ONE_PHASE).
*
* There is no particular upper limit on the size of mapp[], other than
* needing to fit into the metapage. (With 8K block size, 128 bitmaps
* limit us to 64 GB of overflow space...)
* needing to fit into the metapage. (With 8K block size, 1024 bitmaps
* limit us to 256 GB of overflow space...)
*/
#define HASH_MAX_BITMAPS 128
#define HASH_MAX_BITMAPS 1024
#define HASH_SPLITPOINT_PHASE_BITS 2
#define HASH_SPLITPOINT_PHASES_PER_GRP (1 << HASH_SPLITPOINT_PHASE_BITS)