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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 12:17:33 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 12:17:33 +0000
commit5e45211a64149b3c659b90ff2de6fa982a5a93ed (patch)
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Adding upstream version 15.5.upstream/15.5
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+'\" t
+.\" Title: SAVEPOINT
+.\" Author: The PostgreSQL Global Development Group
+.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
+.\" Date: 2023
+.\" Manual: PostgreSQL 15.5 Documentation
+.\" Source: PostgreSQL 15.5
+.\" Language: English
+.\"
+.TH "SAVEPOINT" "7" "2023" "PostgreSQL 15.5" "PostgreSQL 15.5 Documentation"
+.\" -----------------------------------------------------------------
+.\" * Define some portability stuff
+.\" -----------------------------------------------------------------
+.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+.\" http://bugs.debian.org/507673
+.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
+.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+.ie \n(.g .ds Aq \(aq
+.el .ds Aq '
+.\" -----------------------------------------------------------------
+.\" * set default formatting
+.\" -----------------------------------------------------------------
+.\" disable hyphenation
+.nh
+.\" disable justification (adjust text to left margin only)
+.ad l
+.\" -----------------------------------------------------------------
+.\" * MAIN CONTENT STARTS HERE *
+.\" -----------------------------------------------------------------
+.SH "NAME"
+SAVEPOINT \- define a new savepoint within the current transaction
+.SH "SYNOPSIS"
+.sp
+.nf
+SAVEPOINT \fIsavepoint_name\fR
+.fi
+.SH "DESCRIPTION"
+.PP
+\fBSAVEPOINT\fR
+establishes a new savepoint within the current transaction\&.
+.PP
+A savepoint is a special mark inside a transaction that allows all commands that are executed after it was established to be rolled back, restoring the transaction state to what it was at the time of the savepoint\&.
+.SH "PARAMETERS"
+.PP
+\fIsavepoint_name\fR
+.RS 4
+The name to give to the new savepoint\&. If savepoints with the same name already exist, they will be inaccessible until newer identically\-named savepoints are released\&.
+.RE
+.SH "NOTES"
+.PP
+Use
+\fBROLLBACK TO\fR
+to rollback to a savepoint\&. Use
+\fBRELEASE SAVEPOINT\fR
+to destroy a savepoint, keeping the effects of commands executed after it was established\&.
+.PP
+Savepoints can only be established when inside a transaction block\&. There can be multiple savepoints defined within a transaction\&.
+.SH "EXAMPLES"
+.PP
+To establish a savepoint and later undo the effects of all commands executed after it was established:
+.sp
+.if n \{\
+.RS 4
+.\}
+.nf
+BEGIN;
+ INSERT INTO table1 VALUES (1);
+ SAVEPOINT my_savepoint;
+ INSERT INTO table1 VALUES (2);
+ ROLLBACK TO SAVEPOINT my_savepoint;
+ INSERT INTO table1 VALUES (3);
+COMMIT;
+.fi
+.if n \{\
+.RE
+.\}
+.sp
+The above transaction will insert the values 1 and 3, but not 2\&.
+.PP
+To establish and later destroy a savepoint:
+.sp
+.if n \{\
+.RS 4
+.\}
+.nf
+BEGIN;
+ INSERT INTO table1 VALUES (3);
+ SAVEPOINT my_savepoint;
+ INSERT INTO table1 VALUES (4);
+ RELEASE SAVEPOINT my_savepoint;
+COMMIT;
+.fi
+.if n \{\
+.RE
+.\}
+.sp
+The above transaction will insert both 3 and 4\&.
+.PP
+To use a single savepoint name:
+.sp
+.if n \{\
+.RS 4
+.\}
+.nf
+BEGIN;
+ INSERT INTO table1 VALUES (1);
+ SAVEPOINT my_savepoint;
+ INSERT INTO table1 VALUES (2);
+ SAVEPOINT my_savepoint;
+ INSERT INTO table1 VALUES (3);
+
+ \-\- rollback to the second savepoint
+ ROLLBACK TO SAVEPOINT my_savepoint;
+ SELECT * FROM table1; \-\- shows rows 1 and 2
+
+ \-\- release the second savepoint
+ RELEASE SAVEPOINT my_savepoint;
+
+ \-\- rollback to the first savepoint
+ ROLLBACK TO SAVEPOINT my_savepoint;
+ SELECT * FROM table1; \-\- shows only row 1
+COMMIT;
+.fi
+.if n \{\
+.RE
+.\}
+.sp
+The above transaction shows row 3 being rolled back first, then row 2\&.
+.SH "COMPATIBILITY"
+.PP
+SQL requires a savepoint to be destroyed automatically when another savepoint with the same name is established\&. In
+PostgreSQL, the old savepoint is kept, though only the more recent one will be used when rolling back or releasing\&. (Releasing the newer savepoint with
+\fBRELEASE SAVEPOINT\fR
+will cause the older one to again become accessible to
+\fBROLLBACK TO SAVEPOINT\fR
+and
+\fBRELEASE SAVEPOINT\fR\&.) Otherwise,
+\fBSAVEPOINT\fR
+is fully SQL conforming\&.
+.SH "SEE ALSO"
+\fBBEGIN\fR(7), \fBCOMMIT\fR(7), RELEASE SAVEPOINT (\fBRELEASE_SAVEPOINT\fR(7)), \fBROLLBACK\fR(7), ROLLBACK TO SAVEPOINT (\fBROLLBACK_TO_SAVEPOINT\fR(7))