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OPENJPA-2555 add docs for DateFractionDigits

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Mark Struberg 2019-04-05 23:04:44 +02:00
parent a7969c120b
commit d8ddf87a47
1 changed files with 41 additions and 0 deletions
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openjpa-project/src/doc/manual/ref_guide_dbsetup.xml
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@ -1423,6 +1423,27 @@ The SQL function call to obtain the current timestamp from the database.
Defaults to <literal>"CURRENT_TIMESTAMP"</literal>.
</para>
</listitem>
<listitem id="DBDictionary.DateFractionDigits">
<para>
<indexterm>
<primary>
JDBC
</primary>
<secondary>
DateFractionDigits
</secondary>
</indexterm>
<literal>DateFractionDigits</literal>
Some databases support to store sub-second fraction values.
The digits to store can sometimes be configured.
This value defines the default number of digits to store in the database.
A <code>dateFractionDigits=3</code> will e.g. lead to a <code>DATETIME(3)</code> on some databases.
Note that this default can be overwritten to an integer value n per column via
<code>@Column(scale=n)</code>.
A <code>@Column(scale=-1)</code> will set the fraction digits to zero.
</para>
</listitem>
<listitem id="DBDictionary.DatePrecision">
<para>
<indexterm>
@ -3897,6 +3918,26 @@ The <literal>mysql</literal> dictionary also understands the following
properties:
</para>
<itemizedlist>
<listitem id="MySQLDictionary.DateFractionDigits">
<para>
<indexterm>
<primary>
MySQL
</primary>
<secondary>
DateFractionDigits
</secondary>
</indexterm>
<literal>DateFractionDigits</literal>:
Since MySQL 5.8 a timestamp (<code>DATETIME</code>) can store up to 6 sub-second fractions.
The default in MySQL and OpenJPA is 0 for backward compatibility reasons.
This default can be changed by setting <literal>DateFractionDigits</literal> to the number of
sub-second fraction digits to be stored. This will e.g. result in a <code>DATETIME(6)</code> column.
The number of fraction digits to be generated can also be tweaked via the
<code>@Column(scale=n)</code> annotation, where n is the number of digits.
This setting has primarily an impact on the generated SQL.
</para>
</listitem>
<listitem id="MySQLDictionary.DriverDeserializesBlobs">
<para>
<indexterm>