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diff --git a/doc/src/sgml/html/plpgsql-transactions.html b/doc/src/sgml/html/plpgsql-transactions.html new file mode 100644 index 0000000..33d3281 --- /dev/null +++ b/doc/src/sgml/html/plpgsql-transactions.html @@ -0,0 +1,82 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>43.8. Transaction Management</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="plpgsql-cursors.html" title="43.7. Cursors" /><link rel="next" href="plpgsql-errors-and-messages.html" title="43.9. Errors and Messages" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">43.8. Transaction Management</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="plpgsql-cursors.html" title="43.7. Cursors">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="plpgsql.html" title="Chapter 43. PL/pgSQL — SQL Procedural Language">Up</a></td><th width="60%" align="center">Chapter 43. <span class="application">PL/pgSQL</span> — <acronym class="acronym">SQL</acronym> Procedural Language</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="plpgsql-errors-and-messages.html" title="43.9. Errors and Messages">Next</a></td></tr></table><hr /></div><div class="sect1" id="PLPGSQL-TRANSACTIONS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">43.8. Transaction Management</h2></div></div></div><p> + In procedures invoked by the <code class="command">CALL</code> command + as well as in anonymous code blocks (<code class="command">DO</code> command), + it is possible to end transactions using the + commands <code class="command">COMMIT</code> and <code class="command">ROLLBACK</code>. A new + transaction is started automatically after a transaction is ended using + these commands, so there is no separate <code class="command">START + TRANSACTION</code> command. (Note that <code class="command">BEGIN</code> and + <code class="command">END</code> have different meanings in PL/pgSQL.) + </p><p> + Here is a simple example: +</p><pre class="programlisting"> +CREATE PROCEDURE transaction_test1() +LANGUAGE plpgsql +AS $$ +BEGIN + FOR i IN 0..9 LOOP + INSERT INTO test1 (a) VALUES (i); + IF i % 2 = 0 THEN + COMMIT; + ELSE + ROLLBACK; + END IF; + END LOOP; +END; +$$; + +CALL transaction_test1(); +</pre><p> + </p><a id="id-1.8.8.10.4" class="indexterm"></a><p id="PLPGSQL-TRANSACTION-CHAIN"> + A new transaction starts out with default transaction characteristics such + as transaction isolation level. In cases where transactions are committed + in a loop, it might be desirable to start new transactions automatically + with the same characteristics as the previous one. The commands + <code class="command">COMMIT AND CHAIN</code> and <code class="command">ROLLBACK AND + CHAIN</code> accomplish this. + </p><p> + Transaction control is only possible in <code class="command">CALL</code> or + <code class="command">DO</code> invocations from the top level or nested + <code class="command">CALL</code> or <code class="command">DO</code> invocations without any + other intervening command. For example, if the call stack is + <code class="command">CALL proc1()</code> → <code class="command">CALL proc2()</code> + → <code class="command">CALL proc3()</code>, then the second and third + procedures can perform transaction control actions. But if the call stack + is <code class="command">CALL proc1()</code> → <code class="command">SELECT + func2()</code> → <code class="command">CALL proc3()</code>, then the last + procedure cannot do transaction control, because of the + <code class="command">SELECT</code> in between. + </p><p> + Special considerations apply to cursor loops. Consider this example: +</p><pre class="programlisting"> +CREATE PROCEDURE transaction_test2() +LANGUAGE plpgsql +AS $$ +DECLARE + r RECORD; +BEGIN + FOR r IN SELECT * FROM test2 ORDER BY x LOOP + INSERT INTO test1 (a) VALUES (r.x); + COMMIT; + END LOOP; +END; +$$; + +CALL transaction_test2(); +</pre><p> + Normally, cursors are automatically closed at transaction commit. + However, a cursor created as part of a loop like this is automatically + converted to a holdable cursor by the first <code class="command">COMMIT</code> or + <code class="command">ROLLBACK</code>. That means that the cursor is fully + evaluated at the first <code class="command">COMMIT</code> or + <code class="command">ROLLBACK</code> rather than row by row. The cursor is still + removed automatically after the loop, so this is mostly invisible to the + user. + </p><p> + Transaction commands are not allowed in cursor loops driven by commands + that are not read-only (for example <code class="command">UPDATE + ... RETURNING</code>). + </p><p> + A transaction cannot be ended inside a block with exception handlers. + </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="plpgsql-cursors.html" title="43.7. Cursors">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="plpgsql.html" title="Chapter 43. PL/pgSQL — SQL Procedural Language">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="plpgsql-errors-and-messages.html" title="43.9. Errors and Messages">Next</a></td></tr><tr><td width="40%" align="left" valign="top">43.7. Cursors </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 43.9. Errors and Messages</td></tr></table></div></body></html>
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