The relation between "checkpoint_timeout" and "checkpoint_warning" is missing

Hi, PG,

In "18.5.2. Checkpoints" (
http://www.postgresql.org/docs/9.2/static/runtime-config-wal.html#RUNTIME-CONFIG-WAL-CHECKPOINTS),
the relation between "checkpoint_timeout" and "checkpoint_warning" is
missing.

According to the code, "checkpoint_timeout" should be set larger than
"checkpoint_warning", otherwise the warnings will not be generated. The
comments in function: CheckpointerMain() also tell such behavior, which is
in line#473 in "src/backend/postmaster/checkpointer.c":

/*
* We will warn if (a) too soon since last checkpoint (whatever
* caused it) and (b) somebody set the CHECKPOINT_CAUSE_XLOG flag
* since the last checkpoint start. Note in particular that this
* implementation will not generate warnings caused by
* CheckPointTimeout < CheckPointWarning.
*/

I think this's should definitely specified in the documentation.

Best,
Tianyin

--
Tianyin XU,
http://cseweb.ucsd.edu/~tixu/