Re: [GENERAL] About COPY command (and probably file fdw too)
What you suggest is exactly the second option in the first message below but that’s a real lot of overhead. From: Melvin Davidson Sent: Thursday, May 21, 2015 11:48 PM To: Nicolas Paris Cc: Stefan Stefanov ; Forums postgresql Subject: Re: [GENERAL] About COPY command (and probably file fdw too) I understand what you want with regards to skipping columns in input, but rather than wait to see if that feature is added to a future version of PostgreSQL, probably the best work around is to 1. CREATE an intermediate table with all columns in the input text file. 2. COPY into the intermediate table. 3. INSERT into your table SELECT cola, col2, coln from intermediate table. 4. TRUNCATE intermediate table and repeat steps 2 > 4 as needed. On Thu, May 21, 2015 at 4:33 PM, Nicolas Paris wrote: Hi, To me this would be great. Why not the ability to restrict lines too COPY stafflist (userid, username, staffid) FROM 'myfile.txt' WITH (FORMAT text, DELIMITER E'\t', COLUMNS (1, 2, 7), LINES(2:1000,2000:3000), ENCODING 'windows-1250') => subset of full data. 2015-05-21 22:25 GMT+02:00 Stefan Stefanov : Hi, Maybe I need to clarify a little. The suggested option “[SKIP] COLUMNS ” would contain columns' positions in the file so that only some of the columns in a text file would be read into a table. Example: copy the first, second and seventh columns form myfile.txt into table "stafflist". myfile.txt has many columns. COPY stafflist (userid, username, staffid) FROM 'myfile.txt' WITH (FORMAT text, DELIMITER E'\t', COLUMNS (1, 2, 7), ENCODING 'windows-1250') BR, Stefan Оригинално писмо ---- От: Nicolas Paris nipari...@gmail.com Относно: Re: [GENERAL] About COPY command (and probably file fdw too) До: Stefan Stefanov Изпратено на: 20.05.2015 23:21 2015-05-20 22:16 GMT+02:00 Stefan Stefanov : Hi, I have been using COPY .. FROM a lot these days for reading in tabular data and it does a very good job. Still there is an inconvenience when a (large) text file contains more columns than the target table or the columns’ order differs. I can imagine three ways round and none is really nice - - mount the file as a foreign table with all the text file’s columns then insert into the target table a select from the foreign table; - create an intermediate table with all the text file’s columns, copy into it from the file then insert into the target table and finally drop the intermediate table when no more files are expected; - remove the unneeded columns from the file with a text editor prior to COPY-ing. I think that this is happening often in real life and therefore have a suggestion to add this option “[SKIP] COLUMNS ” to the WITH clause of COPY .. FROM. It may be very useful in file fdw too. To be able to re-arrange columns’ order would come as a free bonus for users. Sincerely, Stefan Stefanov Hi, I guess it already does (from documentation): COPY table_name [ ( column_name [, ...] ) ] FROM { 'filename' | STDIN } [ [ WITH ] ( option [, ...] ) ]Then you can order the column_name as the source file has. -- Melvin Davidson I reserve the right to fantasize. Whether or not you wish to share my fantasy is entirely up to you.
Re: [GENERAL] About COPY command (and probably file fdw too)
Hi, I agree, pgloader seems to be right. And yes, it’s a matter of complexity and usability estimation. Stefan From: David G. Johnston Sent: Friday, May 22, 2015 12:19 AM To: Nicolas Paris Cc: Stefan Stefanov ; Forums postgresql Subject: Re: [GENERAL] About COPY command (and probably file fdw too) On Thu, May 21, 2015 at 1:33 PM, Nicolas Paris wrote: Hi, To me this would be great. Why not the ability to restrict lines too COPY stafflist (userid, username, staffid) FROM 'myfile.txt' WITH (FORMAT text, DELIMITER E'\t', COLUMNS (1, 2, 7), LINES(2:1000,2000:3000), ENCODING 'windows-1250') => subset of full data. At some level of complexity it is questionable whether a feature belongs in core that can exist outside of it. While I have not yet personally used pgloader it seems to accomplish much of what is being requested. http://pgloader.io/index.html COPY (and \copy) serves its purpose extremely well but expects the user to deal with any customization needed either before or after it has done its thing. I believe this is for the best since such customizations and tools have no need to operate on the same release cycle as the core PostgreSQL project. David J.
Re: [GENERAL] About COPY command (and probably file fdw too)
You can already do that, natively in Linux/Mac & by adding some simple tools to try & make Windows useful: cat | grep | psql -d -c "copy ;" between grep, sed, tr, awk you can do almost any in-line filtering or text manipulation you are likely to need. Or a bit of Perl/Python... Brent Wood Programme leader: Environmental Information Delivery NIWA DDI: +64 (4) 3860529 Brent Wood Principal Technician - GIS and Spatial Data Management Programme Leader - Environmental Information Delivery +64-4-386-0529 | 301 Evans Bay Parade, Greta Point, Wellington | www.niwa.co.nz<http://www.niwa.co.nz> [NIWA]<http://www.niwa.co.nz> To ensure compliance with legal requirements and to maintain cyber security standards, NIWA's IT systems are subject to ongoing monitoring, activity logging and auditing. This monitoring and auditing service may be provided by third parties. Such third parties can access information transmitted to, processed by and stored on NIWA's IT systems. From: pgsql-general-ow...@postgresql.org on behalf of Nicolas Paris Sent: Friday, May 22, 2015 8:33 AM To: Stefan Stefanov Cc: Forums postgresql Subject: Re: [GENERAL] About COPY command (and probably file fdw too) Hi, To me this would be great. Why not the ability to restrict lines too COPY stafflist (userid, username, staffid) FROM 'myfile.txt' WITH (FORMAT text, DELIMITER E'\t', COLUMNS (1, 2, 7), LINES(2:1000,2000:3000), ENCODING 'windows-1250') => subset of full data. 2015-05-21 22:25 GMT+02:00 Stefan Stefanov mailto:stefanov...@abv.bg>>: Hi, Maybe I need to clarify a little. The suggested option “[SKIP] COLUMNS ” would contain columns' positions in the file so that only some of the columns in a text file would be read into a table. Example: copy the first, second and seventh columns form myfile.txt into table "stafflist". myfile.txt has many columns. COPY stafflist (userid, username, staffid) FROM 'myfile.txt' WITH (FORMAT text, DELIMITER E'\t', COLUMNS (1, 2, 7), ENCODING 'windows-1250') BR, Stefan ---- Оригинално писмо ---- От: Nicolas Paris nipari...@gmail.com<mailto:nipari...@gmail.com> Относно: Re: [GENERAL] About COPY command (and probably file fdw too) До: Stefan Stefanov mailto:stefanov...@abv.bg>> Изпратено на: 20.05.2015 23:21 2015-05-20 22:16 GMT+02:00 Stefan Stefanov : Hi, I have been using COPY .. FROM a lot these days for reading in tabular data and it does a very good job. Still there is an inconvenience when a (large) text file contains more columns than the target table or the columns’ order differs. I can imagine three ways round and none is really nice - - mount the file as a foreign table with all the text file’s columns then insert into the target table a select from the foreign table; - create an intermediate table with all the text file’s columns, copy into it from the file then insert into the target table and finally drop the intermediate table when no more files are expected; - remove the unneeded columns from the file with a text editor prior to COPY-ing. I think that this is happening often in real life and therefore have a suggestion to add this option “[SKIP] COLUMNS ” to the WITH clause of COPY .. FROM. It may be very useful in file fdw too. To be able to re-arrange columns’ order would come as a free bonus for users. Sincerely, Stefan Stefanov Hi, I guess it already does (from documentation): COPY table_name [ ( column_name [, ...] ) ] FROM { 'filename' | STDIN } [ [ WITH ] ( option [, ...] ) ] Then you can order the column_name as the source file has.
Re: [GENERAL] About COPY command (and probably file fdw too)
On Thu, May 21, 2015 at 1:33 PM, Nicolas Paris wrote: > Hi, > > To me this would be great. Why not the ability to restrict lines too > COPY stafflist (userid, username, staffid) > FROM 'myfile.txt' > WITH (FORMAT text, DELIMITER E'\t', COLUMNS (1, 2, 7), > LINES(2:1000,2000:3000), ENCODING 'windows-1250') > => subset of full data. > > At some level of complexity it is questionable whether a feature belongs in core that can exist outside of it. While I have not yet personally used pgloader it seems to accomplish much of what is being requested. http://pgloader.io/index.html COPY (and \copy) serves its purpose extremely well but expects the user to deal with any customization needed either before or after it has done its thing. I believe this is for the best since such customizations and tools have no need to operate on the same release cycle as the core PostgreSQL project. David J.
Re: [GENERAL] About COPY command (and probably file fdw too)
I understand what you want with regards to skipping columns in input, but rather than wait to see if that feature is added to a future version of PostgreSQL, probably the best work around is to 1. CREATE an intermediate table with all columns in the input text file. 2. COPY into the intermediate table. 3. INSERT into your table SELECT cola, col2, coln from intermediate table. 4. TRUNCATE intermediate table and repeat steps 2 > 4 as needed. On Thu, May 21, 2015 at 4:33 PM, Nicolas Paris wrote: > Hi, > > To me this would be great. Why not the ability to restrict lines too > COPY stafflist (userid, username, staffid) > FROM 'myfile.txt' > WITH (FORMAT text, DELIMITER E'\t', COLUMNS (1, 2, 7), > LINES(2:1000,2000:3000), ENCODING 'windows-1250') > => subset of full data. > > > > 2015-05-21 22:25 GMT+02:00 Stefan Stefanov : > >> Hi, >> >> Maybe I need to clarify a little. >> The suggested option “[SKIP] COLUMNS ” would contain >> columns' positions in the file so that only some of the columns in a text >> file would be read into a table. >> Example: copy the first, second and seventh columns form myfile.txt into >> table "stafflist". myfile.txt has many columns. >> COPY stafflist (userid, username, staffid) >> FROM 'myfile.txt' >> WITH (FORMAT text, DELIMITER E'\t', COLUMNS (1, 2, 7), ENCODING >> 'windows-1250') >> >> BR, Stefan >> >> >> >> Оригинално писмо >> От: Nicolas Paris nipari...@gmail.com >> Относно: Re: [GENERAL] About COPY command (and probably file fdw too) >> До: Stefan Stefanov >> Изпратено на: 20.05.2015 23:21 >> >> >> 2015-05-20 22:16 GMT+02:00 Stefan Stefanov : >> >> Hi, >> >> I have been using COPY .. FROM a lot these days for reading in tabular >> data and it does a very good job. Still there is an inconvenience when a >> (large) text file contains more columns than the target table or the >> columns’ order differs. I can imagine three ways round and none is really >> nice - >> - mount the file as a foreign table with all the text file’s columns >> then insert into the target table a select from the foreign table; >> - create an intermediate table with all the text file’s columns, copy >> into it from the file then insert into the target table and finally drop >> the intermediate table when no more files are expected; >> - remove the unneeded columns from the file with a text editor prior to >> COPY-ing. >> I think that this is happening often in real life and therefore have a >> suggestion to add this option “[SKIP] COLUMNS ” to the WITH >> clause of COPY .. FROM. It may be very useful in file fdw too. >> To be able to re-arrange columns’ order would come as a free bonus for >> users. >> >> Sincerely, >> Stefan Stefanov >> >> >> >> >> Hi, >> >> I guess it already does (from documentation): >> >> COPY table_name [ ( column_name [, ...] ) ] >> FROM { 'filename' | STDIN } >> [ [ WITH ] ( option [, ...] ) ] >> >> Then you can order the column_name as the source file has. >> >> > -- *Melvin Davidson* I reserve the right to fantasize. Whether or not you wish to share my fantasy is entirely up to you.
Re: [GENERAL] About COPY command (and probably file fdw too)
Hi, To me this would be great. Why not the ability to restrict lines too COPY stafflist (userid, username, staffid) FROM 'myfile.txt' WITH (FORMAT text, DELIMITER E'\t', COLUMNS (1, 2, 7), LINES(2:1000,2000:3000), ENCODING 'windows-1250') => subset of full data. 2015-05-21 22:25 GMT+02:00 Stefan Stefanov : > Hi, > > Maybe I need to clarify a little. > The suggested option “[SKIP] COLUMNS ” would contain > columns' positions in the file so that only some of the columns in a text > file would be read into a table. > Example: copy the first, second and seventh columns form myfile.txt into > table "stafflist". myfile.txt has many columns. > COPY stafflist (userid, username, staffid) > FROM 'myfile.txt' > WITH (FORMAT text, DELIMITER E'\t', COLUMNS (1, 2, 7), ENCODING > 'windows-1250') > > BR, Stefan > > > > ---- Оригинално писмо > От: Nicolas Paris nipari...@gmail.com > Относно: Re: [GENERAL] About COPY command (and probably file fdw too) > До: Stefan Stefanov > Изпратено на: 20.05.2015 23:21 > > > 2015-05-20 22:16 GMT+02:00 Stefan Stefanov : > > Hi, > > I have been using COPY .. FROM a lot these days for reading in tabular > data and it does a very good job. Still there is an inconvenience when a > (large) text file contains more columns than the target table or the > columns’ order differs. I can imagine three ways round and none is really > nice - > - mount the file as a foreign table with all the text file’s columns then > insert into the target table a select from the foreign table; > - create an intermediate table with all the text file’s columns, copy > into it from the file then insert into the target table and finally drop > the intermediate table when no more files are expected; > - remove the unneeded columns from the file with a text editor prior to > COPY-ing. > I think that this is happening often in real life and therefore have a > suggestion to add this option “[SKIP] COLUMNS ” to the WITH > clause of COPY .. FROM. It may be very useful in file fdw too. > To be able to re-arrange columns’ order would come as a free bonus for > users. > > Sincerely, > Stefan Stefanov > > > > > Hi, > > I guess it already does (from documentation): > > COPY table_name [ ( column_name [, ...] ) ] > FROM { 'filename' | STDIN } > [ [ WITH ] ( option [, ...] ) ] > > Then you can order the column_name as the source file has. > >
Re: [GENERAL] About COPY command (and probably file fdw too)
Hi, Maybe I need to clarify a little. The suggested option “[SKIP] COLUMNS ” would contain columns' positions in the file so that only some of the columns in a text file would be read into a table. Example: copy the first, second and seventh columns form myfile.txt into table "stafflist". myfile.txt has many columns. COPY stafflist (userid, username, staffid) FROM 'myfile.txt' WITH (FORMAT text, DELIMITER E'\t', COLUMNS (1, 2, 7), ENCODING 'windows-1250') BR, Stefan Оригинално писмо От: Nicolas Paris nipari...@gmail.com Относно: Re: [GENERAL] About COPY command (and probably file fdw too) До: Stefan Stefanov Изпратено на: 20.05.2015 23:21 2015-05-20 22:16 GMT+02:00 Stefan Stefanov stefanov...@abv.bg > : Hi, I have been using COPY .. FROM a lot these days for reading in tabular data and it does a very good job. Still there is an inconvenience when a (large) text file contains more columns than the target table or the columns’ order differs. I can imagine three ways round and none is really nice - - mount the file as a foreign table with all the text file’s columns then insert into the target table a select from the foreign table; - create an intermediate table with all the text file’s columns, copy into it from the file then insert into the target table and finally drop the intermediate table when no more files are expected; - remove the unneeded columns from the file with a text editor prior to COPY-ing. I think that this is happening often in real life and therefore have a suggestion to add this option “[SKIP] COLUMNS ” to the WITH clause of COPY .. FROM. It may be very useful in file fdw too. To be able to re-arrange columns’ order would come as a free bonus for users. Sincerely, Stefan Stefanov Hi, I guess it already does (from documentation): COPY table_name [ ( column_name [, ...] ) ] FROM { ' filename ' | STDIN } [ [ WITH ] ( option [, ...] ) ] Then you can order the column_name as the source file has.
Re: [GENERAL] About COPY command (and probably file fdw too)
2015-05-20 22:16 GMT+02:00 Stefan Stefanov : > Hi, > > I have been using COPY .. FROM a lot these days for reading in tabular > data and it does a very good job. Still there is an inconvenience when a > (large) text file contains more columns than the target table or the > columns’ order differs. I can imagine three ways round and none is really > nice - > - mount the file as a foreign table with all the text file’s columns then > insert into the target table a select from the foreign table; > - create an intermediate table with all the text file’s columns, copy into > it from the file then insert into the target table and finally drop the > intermediate table when no more files are expected; > - remove the unneeded columns from the file with a text editor prior to > COPY-ing. > I think that this is happening often in real life and therefore have a > suggestion to add this option “[SKIP] COLUMNS ” to the WITH > clause of COPY .. FROM. It may be very useful in file fdw too. > To be able to re-arrange columns’ order would come as a free bonus for > users. > > Sincerely, > Stefan Stefanov > > > Hi, I guess it already does (from documentation): COPY table_name [ ( column_name [, ...] ) ] FROM { 'filename' | STDIN } [ [ WITH ] ( option [, ...] ) ] Then you can order the column_name as the source file has.