(such as a sort or hash table) before writing to temporary disk files.

If this value is specified without units, it is taken as kilobytes.

The default value is four megabytes (<literal>4MB</literal>).

Note that for a complex query, several sort or hash operations might be

running in parallel; each operation will generally be allowed

to use as much memory as this value specifies before it starts

Note that a complex query might perform several sort and hash

operations at the same time, with each operation generally being

allowed to use as much memory as this value specifies before

it starts

to write data into temporary files. Also, several running

sessions could be doing such operations concurrently.

Therefore, the total memory used could be many times the value

<para>

Hash-based operations are generally more sensitive to memory

availability than equivalent sort-based operations. The

memoryavailable for hashtables is computed by multiplying

memorylimit forahashtable is computed by multiplying

<varname>work_mem</varname> by

<varname>hash_mem_multiplier</varname>. This makes it

possible for hash-based operations to use an amount of memory