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Add bytea datatype to ECPG.

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So far ECPG programs had to treat binary data for bytea column as 'char' type.
But this meant converting from/to escaped format with PQunescapeBytea/
PQescapeBytea() and therefore forcing users to add unnecessary code and cost
for the conversion in runtime. By adding a dedicated datatype for bytea most of
this special handling is no longer needed.

Author: Matsumura-san ("Matsumura, Ryo" <matsumura.ryo@jp.fujitsu.com>)

Discussion: https://postgr.es/m/flat/03040DFF97E6E54E88D3BFEE5F5480F737A141F9@G01JPEXMBYT04
This commit is contained in:
Michael Meskes
2019-02-18 10:20:31 +01:00
parent 3fdc374b5d
commit 050710b369
18 changed files with 985 additions and 51 deletions
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34
doc/src/sgml/ecpg.sgml
View File

@ -917,7 +917,7 @@ do
<row>
<entry><type>character(<replaceable>n</replaceable>)</type>, <type>varchar(<replaceable>n</replaceable>)</type>, <type>text</type></entry>
<entry><type>char[<replaceable>n</replaceable>+1]</type>, <type>VARCHAR[<replaceable>n</replaceable>+1]</type><footnote><para>declared in <filename>ecpglib.h</filename></para></footnote></entry>
<entry><type>char[<replaceable>n</replaceable>+1]</type>, <type>VARCHAR[<replaceable>n</replaceable>+1]</type></entry>
</row>
<row>
@ -947,7 +947,7 @@ do
<row>
<entry><type>bytea</type></entry>
<entry><type>char *</type></entry>
<entry><type>char *</type>, <type>bytea[<replaceable>n</replaceable>]</type></entry>
</row>
</tbody>
</tgroup>
@ -1204,6 +1204,36 @@ EXEC SQL END DECLARE SECTION;
</programlisting>
</para>
</sect4>
<sect4>
<title id="ecpg-type-bytea">bytea</title>
<para>
The handling of the <type>bytea</type> type is also similar to
the <type>VARCHAR</type>. The definition on an array of type
<type>bytea</type> is converted into a named struct for every
variable. A declaration like:
<programlisting>
bytea var[180];
</programlisting>
is converted into:
<programlisting>
struct bytea_var { int len; char arr[180]; } var;
</programlisting>
The member <structfield>arr</structfield> hosts binary format
data. It also can handle even <literal>'\0'</literal> as part of
data unlike <type>VARCHAR</type>.
The data is converted from/to hex format and sent/received by
ecpglib.
</para>
<note>
<para>
<type>bytea</type> variable can be used only when
<xref linkend="guc-bytea-output"/> is set to <literal>hex</literal>.
</para>
</note>
</sect4>
</sect3>
<sect3 id="ecpg-variables-nonprimitive-c">