Jd/Ops misc

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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 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 signficantly reduced

Windows: FlushViewOfFile and FlushFileBuffers
Unix: fsync


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)

test - table with all 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

NB. example gen
jd'gen test f 3'        NB. f with 3 rows
jd'reads from f'
jd'gen ref2 g 5 2 h 3' NB. g 5 rows and 2 extra cols, h 3 rows
jd'reads from g,g.h'
jd'gen one i 3 2'
jd'reads from h'
jd'gen two j 6 k 3'
jd'reads from j'
jd'reads from k'
jdaccess olddan

info returns dynamic col info

some ops are simpler and run faster without dynamics to update


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



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

See Technical|Damaged.

See tutorial log.