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https://github.com/postgres/postgres.git
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1f92630fc4
on CORE previously. This module offers transaction ID's containing the original XID and the transaction epoch as a bigint value to the user level. It also provides a special txid_snapshot data type that contains an entire transactions visibility snapshot information, which is useful to determine if a particular txid was visible to a transaction or not. The module has been tested by porting Slony-I from using its original xxid data type. Jan
58 lines
1.8 KiB
PL/PgSQL
58 lines
1.8 KiB
PL/PgSQL
-- init
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\set ECHO none
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set client_min_messages = 'warning';
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\i txid.sql
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set client_min_messages = 'notice';
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\set ECHO all
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-- i/o
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select '12:13:'::txid_snapshot;
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select '12:13:1,2'::txid_snapshot;
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-- errors
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select '31:12:'::txid_snapshot;
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select '0:1:'::txid_snapshot;
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select '12:13:0'::txid_snapshot;
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select '12:16:14,13'::txid_snapshot;
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select '12:16:14,14'::txid_snapshot;
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create table snapshot_test (
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nr integer,
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snap txid_snapshot
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);
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insert into snapshot_test values (1, '12:13:');
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insert into snapshot_test values (2, '12:20:13,15,18');
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insert into snapshot_test values (3, '100001:100009:100005,100007,100008');
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insert into snapshot_test values (4, '100:150:101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131');
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select snap from snapshot_test order by nr;
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select txid_snapshot_xmin(snap),
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txid_snapshot_xmax(snap),
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txid_snapshot_xip(snap)
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from snapshot_test order by nr;
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select id, txid_visible_in_snapshot(id, snap)
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from snapshot_test, generate_series(11, 21) id
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where nr = 2;
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-- test bsearch
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select id, txid_visible_in_snapshot(id, snap)
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from snapshot_test, generate_series(90, 160) id
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where nr = 4;
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-- test current values also
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select txid_current() >= txid_snapshot_xmin(txid_current_snapshot());
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/* due to lazy xid alloc in 8.3 those are different in 8.2 and 8.3
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select txid_current() < txid_snapshot_xmax(txid_current_snapshot());
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select txid_visible_in_snapshot(txid_current(), txid_current_snapshot());
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*/
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-- test 64bitness
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select txid_snapshot '1000100010001000:1000100010001100:1000100010001012,1000100010001013';
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select txid_visible_in_snapshot('1000100010001012', '1000100010001000:1000100010001100:1000100010001012,1000100010001013');
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select txid_visible_in_snapshot('1000100010001015', '1000100010001000:1000100010001100:1000100010001012,1000100010001013');
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