diff options
Diffstat (limited to 'doc/src/sgml')
| -rw-r--r-- | doc/src/sgml/config.sgml | 5 | ||||
| -rw-r--r-- | doc/src/sgml/func.sgml | 97 |
2 files changed, 70 insertions, 32 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 2ec9c3026cb..384a71a74b2 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.55 2006/04/23 03:39:48 momjian Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.56 2006/04/25 00:25:15 momjian Exp $ --> <chapter Id="runtime-config"> <title>Server Configuration</title> @@ -3279,7 +3279,8 @@ SELECT * FROM parent WHERE key = 2400; <listitem> <para> Abort any statement that takes over the specified number of - milliseconds. If <varname>log_min_error_statement</> is set to + milliseconds, starting from the time the command arrives at the server + from the client. If <varname>log_min_error_statement</> is set to <literal>ERROR</> or lower, the statement that timed out will also be logged. A value of zero (the default) turns off the limitation. diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 0b5fb01e4da..b53bdca6fc3 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.314 2006/04/23 03:39:50 momjian Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.315 2006/04/25 00:25:15 momjian Exp $ --> <chapter id="functions"> <title>Functions and Operators</title> @@ -5303,6 +5303,15 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})'); <primary>now</primary> </indexterm> <indexterm> + <primary>transaction_timestamp</primary> + </indexterm> + <indexterm> + <primary>statement_timestamp</primary> + </indexterm> + <indexterm> + <primary>clock_timestamp</primary> + </indexterm> + <indexterm> <primary>timeofday</primary> </indexterm> @@ -5358,7 +5367,7 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})'); <row> <entry><literal><function>current_timestamp</function></literal></entry> <entry><type>timestamp with time zone</type></entry> - <entry>Date and time; see <xref linkend="functions-datetime-current"> + <entry>Date and time of start of current transaction; see <xref linkend="functions-datetime-current"> </entry> <entry></entry> <entry></entry> @@ -5474,8 +5483,36 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})'); <row> <entry><literal><function>now</function>()</literal></entry> <entry><type>timestamp with time zone</type></entry> - <entry>Current date and time (equivalent to - <function>current_timestamp</function>); see <xref linkend="functions-datetime-current"> + <entry>Date and time of start of current transaction (equivalent to + <function>CURRENT_TIMESTAMP</function>); see <xref linkend="functions-datetime-current"> + </entry> + <entry></entry> + <entry></entry> + </row> + + <row> + <entry><literal><function>transaction_timestamp</function>()</literal></entry> + <entry><type>timestamp with time zone</type></entry> + <entry>Date and time of start of current transaction (equivalent to + <function>CURRENT_TIMESTAMP</function>); see <xref linkend="functions-datetime-current"> + </entry> + <entry></entry> + <entry></entry> + </row> + + <row> + <entry><literal><function>statement_timestamp</function>()</literal></entry> + <entry><type>timestamp with time zone</type></entry> + <entry>Date and time of start of current statement; see <xref linkend="functions-datetime-current"> + </entry> + <entry></entry> + <entry></entry> + </row> + + <row> + <entry><literal><function>clock_timestamp</function>()</literal></entry> + <entry><type>timestamp with time zone</type></entry> + <entry>Current date and time (changes during statement execution); see <xref linkend="functions-datetime-current"> </entry> <entry></entry> <entry></entry> @@ -5484,7 +5521,8 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})'); <row> <entry><literal><function>timeofday</function>()</literal></entry> <entry><type>text</type></entry> - <entry>Current date and time; see <xref linkend="functions-datetime-current"> + <entry>Current date and time (like <function>clock_timestamp</>), but as a Unix-style <type>text</> value; + see <xref linkend="functions-datetime-current"> </entry> <entry></entry> <entry></entry> @@ -6072,7 +6110,7 @@ SELECT TIMESTAMP WITH TIME ZONE '2001-02-16 20:38:40-05' AT TIME ZONE 'MST'; </sect2> <sect2 id="functions-datetime-current"> - <title>Current Date/Time</title> + <title>Date/Time of Transaction Start</title> <indexterm> <primary>date</primary> @@ -6085,8 +6123,8 @@ SELECT TIMESTAMP WITH TIME ZONE '2001-02-16 20:38:40-05' AT TIME ZONE 'MST'; </indexterm> <para> - The following functions are available to obtain the current date and/or - time: + The following functions are available to obtain the date and/or + time of the start of the current transaction: <synopsis> CURRENT_DATE CURRENT_TIME @@ -6139,12 +6177,6 @@ SELECT LOCALTIMESTAMP; </para> <para> - The function <function>now()</function> is the traditional - <productname>PostgreSQL</productname> equivalent to - <function>CURRENT_TIMESTAMP</function>. - </para> - - <para> It is important to know that <function>CURRENT_TIMESTAMP</function> and related functions return the start time of the current transaction; their values do not @@ -6152,26 +6184,31 @@ SELECT LOCALTIMESTAMP; the intent is to allow a single transaction to have a consistent notion of the <quote>current</quote> time, so that multiple modifications within the same transaction bear the same - time stamp. + time stamp. Consider using <function>statement_timestamp</> or + <function>clock_timestamp</> if you need something that changes + more frequently. </para> - <note> - <para> - Other database systems may advance these values more - frequently. - </para> - </note> + <para> + <function>CURRENT_TIMESTAMP</> might not be the + transaction start time on other database systems. + For this reason, and for completeness, + <function>transaction_timestamp</> is provided. + The function <function>now()</function> is the traditional + <productname>PostgreSQL</productname> equivalent to + the SQL-standard <function>CURRENT_TIMESTAMP</function>. + </para> <para> - There is also the function <function>timeofday()</function> which - returns the wall-clock time and advances during transactions. For - historical reasons <function>timeofday()</function> returns a - <type>text</type> string rather than a <type>timestamp</type> - value: -<screen> -SELECT timeofday(); -<lineannotation>Result: </lineannotation><computeroutput>Sat Feb 17 19:07:32.000126 2001 EST</computeroutput> -</screen> + <function>STATEMENT_TIMESTAMP</> is the time the statement + arrived at the server from the client. It is not the time + the command started execution. If multiple commands were + sent as a single query string to the server, each command + has the same <function>STATEMENT_TIMESTAMP</> because they + all arrived at the same time. Also, commands executed + by server-side functions have a <function>STATEMENT_TIMESTAMP</> + based on the time the client sent the query that triggered + the function, not the time the function was executed. </para> <para> |