Jd/Ops misc

close

close

unmap all files and close all locales
does not affect admin or locks

using a table creates all locales and maps all files

creating locales and mapping takes time so close only when necessary

flush

flush - flush mapped file dirty memory pages to disk

a flush after lots of writes can help ensure that data is on disk

close does a flush before it unmaps files if jdcloseflush has been run

disk hardware buffers mean flushed data is not guaranteed
to be on disk in the event of a failure such as loss of power,
but the chance of corrupted disk data is significantly reduced

Windows: FlushViewOfFile and FlushFileBuffers
Unix: fsync

gen

gen types table rows
gen test table rows
gen ref2 table1 rows1 cols table2 rows2
gen one table rows cols
gen two table1 rows1 table2 [rows2]

generate test table(s)

types - table with all col types
test - table with some col types
ref2 - reference table1 aref table2 bref - extra cols
one - table with extras cols
two - default rows2 is <.rows1%10 - suitable for many to one join

option

option space ...

option space 1 to record last command space
option space 0 to not record (reported as _1)

jd'info last' report last cmd, time, space

validate

validate

Runs info validatebad and marks the db damaged if there are problems.

See Technical|Damaged.

See tutorial log.