In the recent blog post SPOOLing Queries with Results in psql, I looked briefly at some PostgreSQL database psql meta-commands and options that can be used to emulate Oracle database's SQL*Plus spooling behavior. In that post, I wrote, "I have not been able to figure out a way to ... have both the query and its results written to the file without needing to use \qecho
." Fortunately, since that writing, a colleague pointed me to the psql option --log-file
(or -L
).
The PostgreSQL psql documentation states that the --log-file
/ -L
option "write[s] all query output into file filename, in addition to the normal output destination." This handy single option prints both the query and its non-error results to the indicated file. For example, if I start psql
with the command "psql -U postgres -L C:\output\albums.txt
" and then run the query select * from albums;
, the generated file C:\output\albums.txt
appears like this:
********* QUERY ********** select * from albums; ************************** title | artist | year ---------------------------+-----------------+------ Back in Black | AC/DC | 1980 Slippery When Wet | Bon Jovi | 1986 Third Stage | Boston | 1986 Hysteria | Def Leppard | 1987 Some Great Reward | Depeche Mode | 1984 Violator | Depeche Mode | 1990 Brothers in Arms | Dire Straits | 1985 Rio | Duran Duran | 1982 Hotel California | Eagles | 1976 Rumours | Fleetwood Mac | 1977 Kick | INXS | 1987 Appetite for Destruction | Guns N' Roses | 1987 Thriller | Michael Jackson | 1982 Welcome to the Real World | Mr. Mister | 1985 Never Mind | Nirvana | 1991 Please | Pet Shop Boys | 1986 The Dark Side of the Moon | Pink Floyd | 1973 Look Sharp! | Roxette | 1988 Songs from the Big Chair | Tears for Fears | 1985 Synchronicity | The Police | 1983 Into the Gap | Thompson Twins | 1984 The Joshua Tree | U2 | 1987 1984 | Van Halen | 1984 (23 rows)
One drawback when using -L
is that any error messages are not written to the file that the queries and successful results are written to. The next screen snapshot demonstrates an error caused by querying from the column name rather than from the table name and the listing after the screen snapshot shows what appears in the output file.
********* QUERY ********** select * from artist; **************************
The output file generated with psql
's -L
option shows the incorrect query, but the generated file does not include the error message that was shown in the psql
terminal application ('ERROR: relation "artist" does not exist'). I don't know of any way to easily ensure that this error message is written to the same file that the query is written to. Redirection of standard output and standard error is a possibility, but then I'd need to redirect the error messages to a different file than the file to which the query and output are being written based on the filename provided with the -L
option.
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