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Improve documentation for COPY ... ON_ERROR ... 

Discussion: https://postgr.es/m/20240126112829.d420b28859fbe84379fdb7ad%40sraoss.co.jp
Author: Yugo Nagata
Reviewed-by: Masahiko Sawada, David G. Johnston, Atsushi Torikoshi
This commit is contained in:
Alexander Korotkov 2024-02-03 01:49:51 +02:00
parent 18dd9d2ed9
commit 40bbc8cf0a
1 changed files with 28 additions and 20 deletions
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48
doc/src/sgml/ref/copy.sgml
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@ -90,6 +90,13 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
in the <structname>pg_stat_progress_copy</structname> view. See
<xref linkend="copy-progress-reporting"/> for details.
</para>
<para>
By default, <command>COPY</command> will fail if it encounters an error
during processing. For use cases where a best-effort attempt at loading
the entire file is desired, the <literal>ON_ERROR</literal> clause can
be used to specify some other behavior.
</para>
</refsect1>
<refsect1>
@ -378,17 +385,20 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
<term><literal>ON_ERROR</literal></term>
<listitem>
<para>
Specifies which <replaceable class="parameter">
error_action</replaceable> to perform when there is malformed data in the input.
Currently, only <literal>stop</literal> (default) and <literal>ignore</literal>
values are supported.
If the <literal>stop</literal> value is specified,
<command>COPY</command> stops operation at the first error.
If the <literal>ignore</literal> value is specified,
<command>COPY</command> skips malformed data and continues copying data.
The option is allowed only in <command>COPY FROM</command>.
Only <literal>stop</literal> value is allowed when
using <literal>binary</literal> format.
Specifies how to behave when encountering an error converting a column's
input value into its data type.
An <replaceable class="parameter">error_action</replaceable> value of
<literal>stop</literal> means fail the command, while
<literal>ignore</literal> means discard the input row and continue with the next one.
The default is <literal>stop</literal>.
</para>
<para>
The <literal>ignore</literal> option is applicable only for <command>COPY FROM</command>
when the <literal>FORMAT</literal> is <literal>text</literal> or <literal>csv</literal>.
</para>
<para>
A <literal>NOTICE</literal> message containing the ignored row count is emitted at the end
of the <command>COPY FROM</command> if at least one row was discarded.
</para>
</listitem>
</varlistentry>
@ -576,15 +586,13 @@ COPY <replaceable class="parameter">count</replaceable>
</para>
<para>
<command>COPY</command> stops operation at the first error when
<literal>ON_ERROR</literal> is not specified. This
should not lead to problems in the event of a <command>COPY
TO</command>, but the target table will already have received
earlier rows in a <command>COPY FROM</command>. These rows will not
be visible or accessible, but they still occupy disk space. This might
amount to a considerable amount of wasted disk space if the failure
happened well into a large copy operation. You might wish to invoke
<command>VACUUM</command> to recover the wasted space.
The <command>COPY FROM</command> command physically inserts input rows
into the table as it progresses. If the command fails, these rows are
left in a deleted state; these rows will not be visible, but still
occupy disk space. This might amount to considerable
wasted disk space if the failure happened well into a large copy
operation. <command>VACUUM</command> should be used to recover the
wasted space.
</para>
<para>