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If your connection to the database server is lost while a COMMIT is in progress, it may be difficult to figure out whether the COMMIT was successful or not. This function will tell you, provided that you don't wait too long to ask. It may be useful in other situations, too. Craig Ringer, reviewed by Simon Riggs and by me Discussion: http://postgr.es/m/CAMsr+YHQiWNEi0daCTboS40T+V5s_+dst3PYv_8v2wNVH+Xx4g@mail.gmail.com
100 lines
2.9 KiB
PL/PgSQL
100 lines
2.9 KiB
PL/PgSQL
-- txid_snapshot data type and related functions
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-- i/o
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select '12:13:'::txid_snapshot;
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select '12:18:14,16'::txid_snapshot;
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select '12:16:14,14'::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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create temp 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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-- we can't assume current is always less than xmax, however
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select txid_visible_in_snapshot(txid_current(), txid_current_snapshot());
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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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-- test 64bit overflow
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SELECT txid_snapshot '1:9223372036854775807:3';
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SELECT txid_snapshot '1:9223372036854775808:3';
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-- test txid_current_if_assigned
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BEGIN;
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SELECT txid_current_if_assigned() IS NULL;
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SELECT txid_current() \gset
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SELECT txid_current_if_assigned() IS NOT DISTINCT FROM BIGINT :'txid_current';
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COMMIT;
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-- test xid status functions
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BEGIN;
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SELECT txid_current() AS committed \gset
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COMMIT;
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BEGIN;
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SELECT txid_current() AS rolledback \gset
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ROLLBACK;
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BEGIN;
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SELECT txid_current() AS inprogress \gset
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SELECT txid_status(:committed) AS committed;
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SELECT txid_status(:rolledback) AS rolledback;
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SELECT txid_status(:inprogress) AS inprogress;
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SELECT txid_status(1); -- BootstrapTransactionId is always committed
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SELECT txid_status(2); -- FrozenTransactionId is always committed
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SELECT txid_status(3); -- in regress testing FirstNormalTransactionId will always be behind oldestXmin
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COMMIT;
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BEGIN;
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CREATE FUNCTION test_future_xid_status(bigint)
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RETURNS void
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LANGUAGE plpgsql
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AS
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$$
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BEGIN
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PERFORM txid_status($1);
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RAISE EXCEPTION 'didn''t ERROR at xid in the future as expected';
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EXCEPTION
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WHEN invalid_parameter_value THEN
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RAISE NOTICE 'Got expected error for xid in the future';
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END;
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$$;
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SELECT test_future_xid_status(:inprogress + 10000);
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ROLLBACK;
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