Age Owner TLA Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * discard.c
4 : * The implementation of the DISCARD command
5 : *
6 : * Copyright (c) 1996-2023, PostgreSQL Global Development Group
7 : *
8 : *
9 : * IDENTIFICATION
10 : * src/backend/commands/discard.c
11 : *
12 : *-------------------------------------------------------------------------
13 : */
14 : #include "postgres.h"
15 :
16 : #include "access/xact.h"
17 : #include "catalog/namespace.h"
18 : #include "commands/async.h"
19 : #include "commands/discard.h"
20 : #include "commands/prepare.h"
21 : #include "commands/sequence.h"
22 : #include "utils/guc.h"
23 : #include "utils/portal.h"
24 :
25 : static void DiscardAll(bool isTopLevel);
26 :
27 : /*
28 : * DISCARD { ALL | SEQUENCES | TEMP | PLANS }
29 : */
30 : void
5624 bruce 31 CBC 15 : DiscardCommand(DiscardStmt *stmt, bool isTopLevel)
32 : {
5827 neilc 33 15 : switch (stmt->target)
34 : {
35 3 : case DISCARD_ALL:
36 3 : DiscardAll(isTopLevel);
37 3 : break;
38 :
39 2 : case DISCARD_PLANS:
40 2 : ResetPlanCache();
41 2 : break;
42 :
3475 rhaas 43 6 : case DISCARD_SEQUENCES:
44 6 : ResetSequenceCaches();
45 6 : break;
46 :
5827 neilc 47 4 : case DISCARD_TEMP:
48 4 : ResetTempTableNamespace();
49 4 : break;
50 :
5827 neilc 51 UBC 0 : default:
52 0 : elog(ERROR, "unrecognized DISCARD target: %d", stmt->target);
53 : }
5827 neilc 54 CBC 15 : }
55 :
56 : static void
57 3 : DiscardAll(bool isTopLevel)
58 : {
59 : /*
60 : * Disallow DISCARD ALL in a transaction block. This is arguably
61 : * inconsistent (we don't make a similar check in the command sequence
62 : * that DISCARD ALL is equivalent to), but the idea is to catch mistakes:
63 : * DISCARD ALL inside a transaction block would leave the transaction
64 : * still uncommitted.
65 : */
1878 peter_e 66 3 : PreventInTransactionBlock(isTopLevel, "DISCARD ALL");
67 :
68 : /* Closing portals might run user-defined code, so do that first. */
4424 tgl 69 3 : PortalHashTableDeleteAll();
5827 neilc 70 3 : SetPGVariable("session_authorization", NIL, false);
71 3 : ResetAllOptions();
72 3 : DropAllPreparedStatements();
73 3 : Async_UnlistenAll();
5247 tgl 74 3 : LockReleaseAll(USER_LOCKMETHOD, true);
5827 neilc 75 3 : ResetPlanCache();
76 3 : ResetTempTableNamespace();
3475 rhaas 77 3 : ResetSequenceCaches();
5827 neilc 78 3 : }
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