While talking to Amit Kapila this morning, he mentioned to me that
there seem to be no CHECK_FOR_INTERRUPTS() calls anywhere in
heap_multi_insert() or the functions it calls. Should there be?

By way of contrast, heapgetpage() has this:

     * Be sure to check for interrupts at least once per page.  Checks at
     * higher code levels won't be able to stop a seqscan that encounters many
     * pages' worth of consecutive dead tuples.

In heap_multi_insert(), we first do heap_prepare_insert() on each
tuple, which may involve dirtying many pages, since it handles TOAST.
Then, we loop over the tuples themselves and dirty a bunch more pages.
All of that will normally happen pretty quickly, but if the I/O
subsystem is very slow for some reason, such as due to heavy system
load, then it might take quite a long time.  I'm thinking we might
want a CHECK_FOR_INTERRUPTS() in the following two places:

1. Inside toast_save_datum, at the top of the loop that starts with
"while (data_todo > 0)".
2. Inside heap_multi_insert, at the top of the loop that starts with
"while (ndone < ntuples)".


Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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