On 10/17/2013 02:42 PM, Robert Haas wrote:
> On Thu, Oct 17, 2013 at 8:26 AM, Vik Fearing <[email protected]> wrote:
>> On 10/17/2013 10:03 AM, Fabien COELHO wrote:
>>> My guess is that it won't be committed if there is a single "but it
>>> might break one code or surprise one user somewhere in the universe",
>>> but I wish I'll be proven wrong. IMO, "returned with feedback" on a 1
>>> liner is really akin to "rejected".
>> I have attached here an entirely new patch (new documentation and
>> everything) that should please everyone. It no longer overloads
>> pg_sleep(double precision) but instead add two new functions:
>>
>> * pg_sleep_for(interval)
>> * pg_sleep_until(timestamp with time zone)
>>
>> Because it's no longer overloading the original pg_sleep, Robert's
>> ambiguity objection is no more.
>>
>> Also, I like how it reads aloud: SELECT pg_sleep_for('5 minutes');
>>
>> If people like this, I'll reject the current patch and add this one to
>> the next commitfest.
> I find that naming relatively elegant. However, you've got to
> schema-qualify every function and operator used in the definitions, or
> you're creating a search-path security vulnerability.
>
Good catch. Updated patch attached.
--
Vik
*** a/doc/src/sgml/func.sgml
--- b/doc/src/sgml/func.sgml
***************
*** 7586,7605 **** SELECT TIMESTAMP 'now'; -- incorrect for use with DEFAULT
</indexterm>
<para>
! The following function is available to delay execution of the server
process:
<synopsis>
pg_sleep(<replaceable>seconds</replaceable>)
</synopsis>
<function>pg_sleep</function> makes the current session's process
sleep until <replaceable>seconds</replaceable> seconds have
elapsed. <replaceable>seconds</replaceable> is a value of type
<type>double precision</>, so fractional-second delays can be specified.
For example:
<programlisting>
SELECT pg_sleep(1.5);
</programlisting>
</para>
--- 7586,7613 ----
</indexterm>
<para>
! The following functions are available to delay execution of the server
process:
<synopsis>
pg_sleep(<replaceable>seconds</replaceable>)
+ pg_sleep_for(<type>interval</>)
+ pg_sleep_until(<type>timestamp with time zone</>)
</synopsis>
<function>pg_sleep</function> makes the current session's process
sleep until <replaceable>seconds</replaceable> seconds have
elapsed. <replaceable>seconds</replaceable> is a value of type
<type>double precision</>, so fractional-second delays can be specified.
+ <function>pg_sleep_for</function> is a convenience function for larger
+ sleep times specified as an <type>interval</>.
+ <function>pg_sleep_until</function> is a convenience function for when
+ a specific wake-up time is desired.
For example:
<programlisting>
SELECT pg_sleep(1.5);
+ SELECT pg_sleep_for('5 minutes');
+ SELECT pg_sleep_until('tomorrow 03:00');
</programlisting>
</para>
***************
*** 7608,7622 **** SELECT pg_sleep(1.5);
The effective resolution of the sleep interval is platform-specific;
0.01 seconds is a common value. The sleep delay will be at least as long
as specified. It might be longer depending on factors such as server load.
</para>
</note>
<warning>
<para>
Make sure that your session does not hold more locks than necessary
! when calling <function>pg_sleep</function>. Otherwise other sessions
! might have to wait for your sleeping process, slowing down the entire
! system.
</para>
</warning>
</sect2>
--- 7616,7632 ----
The effective resolution of the sleep interval is platform-specific;
0.01 seconds is a common value. The sleep delay will be at least as long
as specified. It might be longer depending on factors such as server load.
+ In particular, <function>pg_sleep_until</function> is not guaranteed to
+ wake up exactly at the specified time, but it will not wake up any earlier.
</para>
</note>
<warning>
<para>
Make sure that your session does not hold more locks than necessary
! when calling <function>pg_sleep</function> or its variants. Otherwise
! other sessions might have to wait for your sleeping process, slowing down
! the entire system.
</para>
</warning>
</sect2>
*** a/src/include/catalog/pg_proc.h
--- b/src/include/catalog/pg_proc.h
***************
*** 3017,3022 **** DATA(insert OID = 2625 ( pg_ls_dir PGNSP PGUID 12 1 1000 0 0 f f f f t t v 1 0
--- 3017,3026 ----
DESCR("list all files in a directory");
DATA(insert OID = 2626 ( pg_sleep PGNSP PGUID 12 1 0 0 0 f f f f t f v 1 0 2278 "701" _null_ _null_ _null_ _null_ pg_sleep _null_ _null_ _null_ ));
DESCR("sleep for the specified time in seconds");
+ DATA(insert OID = 3179 ( pg_sleep_for PGNSP PGUID 14 1 0 0 0 f f f f t f v 1 0 2278 "1186" _null_ _null_ _null_ _null_ "select pg_catalog.pg_sleep(extract(epoch from pg_catalog.now() operator(pg_catalog.+) $1) operator(pg_catalog.-) extract(epoch from pg_catalog.now()))" _null_ _null_ _null_ ));
+ DESCR("sleep for the specified interval");
+ DATA(insert OID = 3180 ( pg_sleep_until PGNSP PGUID 14 1 0 0 0 f f f f t f v 1 0 2278 "1184" _null_ _null_ _null_ _null_ "select pg_catalog.pg_sleep(extract(epoch from $1) operator(pg_catalog.-) extract(epoch from pg_catalog.now()))" _null_ _null_ _null_ ));
+ DESCR("sleep until the specified time");
DATA(insert OID = 2971 ( text PGNSP PGUID 12 1 0 0 0 f f f f t f i 1 0 25 "16" _null_ _null_ _null_ _null_ booltext _null_ _null_ _null_ ));
DESCR("convert boolean to text");
*** a/src/test/regress/expected/stats.out
--- b/src/test/regress/expected/stats.out
***************
*** 18,26 **** SET enable_indexscan TO on;
SET enable_indexonlyscan TO off;
-- wait to let any prior tests finish dumping out stats;
-- else our messages might get lost due to contention
! SELECT pg_sleep(2.0);
! pg_sleep
! ----------
(1 row)
--- 18,26 ----
SET enable_indexonlyscan TO off;
-- wait to let any prior tests finish dumping out stats;
-- else our messages might get lost due to contention
! SELECT pg_sleep_for('2 seconds');
! pg_sleep_for
! --------------
(1 row)
*** a/src/test/regress/sql/stats.sql
--- b/src/test/regress/sql/stats.sql
***************
*** 16,22 **** SET enable_indexonlyscan TO off;
-- wait to let any prior tests finish dumping out stats;
-- else our messages might get lost due to contention
! SELECT pg_sleep(2.0);
-- save counters
CREATE TEMP TABLE prevstats AS
--- 16,22 ----
-- wait to let any prior tests finish dumping out stats;
-- else our messages might get lost due to contention
! SELECT pg_sleep_for('2 seconds');
-- save counters
CREATE TEMP TABLE prevstats AS
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