Jd/Ops misc
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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.