I have multiple tables that are created in the same way (same columns, indexes, etc.)
I would like to have one sql file for creating them all without duplicating the create statements.
Is there a way to use some kind of placeholder in sql file which would be substituted when executing the sql file with a parameter?
For example I would like to have below sql statement:
drop table if exists schema.%PLACEHOLDER%;
create table schema.%PLACEHOLDER%(id text, data text);
And execute such script with:
psql -f mysqlfile.sql -magic_parameter my_desired_table_name
Is this possible when executing PostgreSQL sql files, or maybe other way to achieve the same (except using sed)?
Sincr you are using psql, you can use variables as follows:
drop table if exists schema.:placeholder;
The invocation is:
psql -f mysqlfile.sql -v placeholder=table_name
Related
I'm familiarizing myself with the standalone version of Datagrip and having a bit of trouble understanding the different approaches to composing SQL via console, external files, scratch files, etc.
I'm managing, referencing the documentation, and am happy to figure things out as such.
However, I'm trying to ingest CSV data into tables via batch files using the Postgres \copy command. Datagrip will execute this command without error but no data is being populated.
This is my syntax, composed and ran in the console view:
\copy tablename from 'C:\Users\username\data_file.txt' WITH DELIMITER E'\t' csv;
Note that the data is tab-separated and stored in a .txt file.
I'm able to use the import functions of Datagrip (via context menu) just fine but I'd like to understand how to issue commands to do similarly.
\copy is a command of the command-line PostgreSQL client psql.
I doubt that Datagrip invokes psql, so it won't be able to use \copy or any other “backslash command”.
You probably have to use Datagrip's import facilities. Or you start using psql.
Ok, but what about the SQL COPY command https://www.postgresql.org/docs/12/sql-copy.html ?
How can I run something like that with datagrip ?
BEGIN;
CREATE TEMPORARY TABLE temp_json(values text) ON COMMIT DROP;
COPY temp_json FROM 'MY_FILE.JSON';
SELECT values->>'aJsonField' as f
FROM (select values::json AS values FROM temp_json) AS a;
COMMIT;
I try to replace 'MY_FILE.JSON' with full path, parameter (?), I put it in sql directory etc.
The data grip answer is :
[2021-05-05 10:30:45] [58P01] ERROR: could not open file '...' for reading : No such file or directory
EDIT :
I know why. RTFM! -_-
COPY with a file name instructs the PostgreSQL server to directly read from or write to a file. The file must be accessible by the PostgreSQL user (the user ID the server runs as) and the name must be specified from the viewpoint of the server.
Sorry.....
I have a table on pgadmin4 which consist of 100.000 lines and 23 columns.I need to benchmark postgresql on this specific table using pgbench,but i cant understand what parameters should i use.The database name is desdb and table called test.
PgAdmin4 is not a database server, it is a client. You don't have tables "on" pgadmin4, pgadmin4 is just one way of accessing tables which are on an actual server.
You don't benchmark tables, you benchmark queries. Knowing nothing about the table other than its name, all I could propose for a query is something like:
select * from test
Or
select count(*) from test
You could put that in a file test.sql, then run:
pgbench -n -f test.sql -T60 -P5 desdb
If you are like me and don't like littering your filesystem with bunches of tiny files with contents of no particular interest and you if use the bash shell, you could not create a test.sql file and instead make it dynamic:
pgbench -n -f <(echo 'select * from test') -T60 -P5 desdb
Whether that is a meaningful query to be benchmarking, I don't know. Do you care about how fast you can read (and then throw away) all columns for all rows in the table?
you can refer details regarding pgbench from : https://www.cloudbees.com/blog/tuning-postgresql-with-pgbench.
DB2 command to Postgres command.
db2 IMPORT FROM test.csv OF DEL MODIFIED BY USEDEFAULTS COMMITCOUNT 100000 "INSERT_UPDATE INTO TEST.person (name,old,sex)" > ${TEMPTXT}
How can i use postgres command to do the same thing like this db2 command to import from file to insert and update the table ?
Postgres has COPY, but it doesn't perform update.So, first run COPY into a TEMP table and then merge into main table.
For a comma delimiter,
CREATE TEMP TABLE TEST.tmp_person (name text,old text,sex text)
COPY TEST.tmp_person FROM test.csv WITH DELIMITER ',' CSV
-- ^temp table
There are various techniques in Postgres to do INSERT_UPDATE or merge. Refer this post. Use proper casting to appropriate target data types while inserting/updating.
I have my database hosted on heroku, and I want to download specific parts of the database (e.g. all the rows with id > x from table 1, all the rows with name = x from table 2, etc.) in a single file.
From some research and asking a question here it seems that some kind of modified pg_dump would solve my problem. However, I won't be able to use pg_dump because I won't have access to the command line (basically I want to be able to click a button in my web app and it will generate + download the database file).
So my new strategy is to use the postgres copy command. I'll go through the various tables in my server database, run COPY (Select * FROM ... WHERE ...) TO filename , where filename is just a temporary file that I will download when complete.
The issue is that this filename file will just have the rows, so I can't just turn around and import it into pgadmin. Assuming I have an 'empty' database set up (the schema, indices, and stuff are all already set up), is there a way I can format my filename file so that it can be easily imported into a postgres db?
Building on my comment about to/from stdout/stdin, and answering the actual question about including multiple tables in one file; you can construct the output file to interleave copy ... from stdin with actual data and load it via psql. For example, psql will support input files that look like this:
copy my_table (col1, col2, col3) from stdin;
foo bar baz
fizz buzz bizz
\.
(Note the trailing \. and that the separators should be tabs; you could also specify the delimiter option in the copy command).
psql will treat everything between the ';' and '.' as stdin. This essentially emulates what pg_dump does when you export table data and no schema (e.g., pg_dump -a -t my_table).
The resulting load could be as simple as psql mydb < output.dump.
Please help to create postgresql query equal to mysql query
LOAD DATA LOCAL INFILE 'file.txt' REPLACE INTO TABLE newtable TERMINATED BY ',' IGNORE 1 LINES;
There is no equivalent feature in PostgreSQL - at least in the current 9.3 or any prior version.
You must do this in a few steps:
CREATE TEMPORARY TABLE ...
COPY into the temp table
Do an UPDATE ... FROM followed by an INSERT INTO ... WHERE NOT EXISTS (...) to merge data
DROP the temp table
Search for "postgresql bulk upsert" or "postgresql copy upsert".
you might be looking for COPY
COPY will be run by the PostgreSQL backend (user "postgres"). The backend user requires permissions to read & write to the data file in order to copy from/to it. You need to use an absolute pathname with COPY. \COPY on the other hand, runs under the current $USER, and with that users environment. And \COPY can handle relative pathnames. The psql \COPY is accordingly much easier to use if it handles what you need.