A trigger seems to be ignoring the 'when condition' in my definition but I'm unsure why. I'm running the following:
create trigger trigger_update_candidate_location
after update on candidates
for each row
when (
OLD.address1 is distinct from NEW.address1
or
OLD.address2 is distinct from NEW.address2
or
OLD.city is distinct from NEW.city
or
OLD.state is distinct from NEW.state
or
OLD.zip is distinct from NEW.zip
or
OLD.country is distinct from NEW.country
)
execute procedure entities.tf_update_candidate_location();
But when I check back in on it, I get the following:
-- auto-generated definition
create trigger trigger_update_candidate_location
after update
on candidates
for each row
execute procedure tf_update_candidate_location();
This is problematic because the procedure I call ends up doing an update on the same table for different columns (lat/lng). Since the 'when' condition is ignored this crates an infinite loop.
My intention is to watch for address change, do a lookup on another table to get lat/lng values.
Postgresql version: 10.6
IDE: DataGrip 2018.1.3
How exactly do you create and "check back"? With datagrip?
The WHEN condition was added with Postgres 9.0. Some old (or poor) clients may be outdated. To be sure, check in pgsql with:
SELECT pg_get_triggerdef(oid, true)
FROM pg_trigger
WHERE tgrelid = 'candidates'::regclass -- schema-qualify name to be sure
AND NOT tgisinternal;
Any actual WHEN qualification is stored in internal format in pg_trigger.tgqual, btw. Details in the manual here.
Also what's your current search_path and what's the schema of table candidates?
It stands out that the table candidates is unqualified, while the trigger function entities.tf_update_candidate_location() has a schema-qualification ... You are not confusing tables of the same name in different DB schemas, are you?
Aside, you can simplify with this shorter, equivalent syntax:
create trigger trigger_update_candidate_location
after update on candidates -- schema-qualify??
for each row
when (
(OLD.address1, OLD.address2, OLD.city, OLD.state, OLD.zip, OLD.country)
IS DISTINCT FROM
(NEW.address1, NEW.address2, NEW.city, NEW.state, NEW.zip, NEW.country)
)
execute procedure entities.tf_update_candidate_location();
Unfortunately, that's the issue of DataGrip. Please follow the ticket to be notified when it's fixed.
https://youtrack.jetbrains.com/issue/DBE-7247
I want to do an upset in postgres (insert or update)
If a user_id does not exist in the table, I want to insert a line with user_id=user_id, first_date=date, last_date=date. But if the user already exists, I want to update only the last_date with date.
I was getting an error so I tried to simplify the insert with:
pd.read_sql("INSERT INTO table (user_id, first_date, last_date)
VALUES ( "+str(user_id)+", '"+date+"','"+date+"')
ON CONFLICT (user_id)
DO NOTHING", conn)
But I'm getting this error "TypeError: 'NoneType' object is not iterable"
And I can't understand what is wrong...
I'm using Jupyter and Postgres v11
read_sql expects a query returning data. Your INSERT doesn't.
You might use the execute function the documentation:
from pandas.io import sql
sql.execute('INSERT INTO table_name VALUES(?, ?, ?)', engine,
params=[('id', 1, 12.2, True)])
or you could add a RETURNING clause to the query. See the excellent postgresql documentation.
There is a constraint violation handling "On conflict" statement, working fine if i want to check 1 (!) constraint
For example :
INSERT INTO my_table (co1,col2..colN)
VALUES (...)
ON CONFLICT (col1, col2) DO NOTHING --or update
But if i have 2 constaints unique(col1,col2) and unique(col5,col6,col7) , the query below is not working :
INSERT INTO my_table (co1,col2..colN)
VALUES (...)
ON CONFLICT (col1, col2) DO NOTHING --or update
ON CONFLICT (col5, col6, col7) DO NOTHING --or update
This raises the error, pointing on : ERROR: syntax error at or near "on". LINE _: on conflict (col5, col6, col7) do nothing
How could i resolve using multiple constraint checking in one query?
As per the documentation:
For ON CONFLICT DO NOTHING, it is optional to specify a conflict_target; when omitted, conflicts with all usable constraints (and unique indexes) are handled. For ON CONFLICT DO UPDATE, a conflict_target must be provided.
So, you can just write:
INSERT INTO my_table (co1,col2..colN)
VALUES (...)
ON CONFLICT DO NOTHING
This doesn't work for DO UPDATE, though. However, we might soon get treated to the standard SQL MERGE statement in PostgreSQL, in case of which you could do these more complex conflict resolutions manually.
The error message is kinda vague... The query below works on one server, but fails on another:
INSERT INTO searches (status, uid, datecreated, searchname, options)
VALUES (0, 1, NOW(), 'TEST', '16') RETURNING sid;
And I get this error:
Query failed: ERROR: syntax error at or near "RETURNING"
Am I missing something here?
Query certainly looks right - assuming the field sid does exist (I take it it's a SERIAL field).
Are you sure you're using a PostgreSQL version that has support for RETURNING? You need version 8.2 or newer for this.
Some SQL servers have a feature where INSERT is skipped if it would violate a primary/unique key constraint. For instance, MySQL has INSERT IGNORE.
What's the best way to emulate INSERT IGNORE and ON DUPLICATE KEY UPDATE with PostgreSQL?
With PostgreSQL 9.5, this is now native functionality (like MySQL has had for several years):
INSERT ... ON CONFLICT DO NOTHING/UPDATE ("UPSERT")
9.5 brings support for "UPSERT" operations.
INSERT is extended to accept an ON CONFLICT DO UPDATE/IGNORE clause. This clause specifies an alternative action to take in the event of a would-be duplicate violation.
...
Further example of new syntax:
INSERT INTO user_logins (username, logins)
VALUES ('Naomi',1),('James',1)
ON CONFLICT (username)
DO UPDATE SET logins = user_logins.logins + EXCLUDED.logins;
Edit: in case you missed warren's answer, PG9.5 now has this natively; time to upgrade!
Building on Bill Karwin's answer, to spell out what a rule based approach would look like (transferring from another schema in the same DB, and with a multi-column primary key):
CREATE RULE "my_table_on_duplicate_ignore" AS ON INSERT TO "my_table"
WHERE EXISTS(SELECT 1 FROM my_table
WHERE (pk_col_1, pk_col_2)=(NEW.pk_col_1, NEW.pk_col_2))
DO INSTEAD NOTHING;
INSERT INTO my_table SELECT * FROM another_schema.my_table WHERE some_cond;
DROP RULE "my_table_on_duplicate_ignore" ON "my_table";
Note: The rule applies to all INSERT operations until the rule is dropped, so not quite ad hoc.
For those of you that have Postgres 9.5 or higher, the new ON CONFLICT DO NOTHING syntax should work:
INSERT INTO target_table (field_one, field_two, field_three )
SELECT field_one, field_two, field_three
FROM source_table
ON CONFLICT (field_one) DO NOTHING;
For those of us who have an earlier version, this right join will work instead:
INSERT INTO target_table (field_one, field_two, field_three )
SELECT source_table.field_one, source_table.field_two, source_table.field_three
FROM source_table
LEFT JOIN target_table ON source_table.field_one = target_table.field_one
WHERE target_table.field_one IS NULL;
Try to do an UPDATE. If it doesn't modify any row that means it didn't exist, so do an insert. Obviously, you do this inside a transaction.
You can of course wrap this in a function if you don't want to put the extra code on the client side. You also need a loop for the very rare race condition in that thinking.
There's an example of this in the documentation: http://www.postgresql.org/docs/9.3/static/plpgsql-control-structures.html, example 40-2 right at the bottom.
That's usually the easiest way. You can do some magic with rules, but it's likely going to be a lot messier. I'd recommend the wrap-in-function approach over that any day.
This works for single row, or few row, values. If you're dealing with large amounts of rows for example from a subquery, you're best of splitting it into two queries, one for INSERT and one for UPDATE (as an appropriate join/subselect of course - no need to write your main filter twice)
To get the insert ignore logic you can do something like below. I found simply inserting from a select statement of literal values worked best, then you can mask out the duplicate keys with a NOT EXISTS clause. To get the update on duplicate logic I suspect a pl/pgsql loop would be necessary.
INSERT INTO manager.vin_manufacturer
(SELECT * FROM( VALUES
('935',' Citroën Brazil','Citroën'),
('ABC', 'Toyota', 'Toyota'),
('ZOM',' OM','OM')
) as tmp (vin_manufacturer_id, manufacturer_desc, make_desc)
WHERE NOT EXISTS (
--ignore anything that has already been inserted
SELECT 1 FROM manager.vin_manufacturer m where m.vin_manufacturer_id = tmp.vin_manufacturer_id)
)
INSERT INTO mytable(col1,col2)
SELECT 'val1','val2'
WHERE NOT EXISTS (SELECT 1 FROM mytable WHERE col1='val1')
As #hanmari mentioned in his comment. when inserting into a postgres tables, the on conflict (..) do nothing is the best code to use for not inserting duplicate data.:
query = "INSERT INTO db_table_name(column_name)
VALUES(%s) ON CONFLICT (column_name) DO NOTHING;"
The ON CONFLICT line of code will allow the insert statement to still insert rows of data. The query and values code is an example of inserted date from a Excel into a postgres db table.
I have constraints added to a postgres table I use to make sure the ID field is unique. Instead of running a delete on rows of data that is the same, I add a line of sql code that renumbers the ID column starting at 1.
Example:
q = 'ALTER id_column serial RESTART WITH 1'
If my data has an ID field, I do not use this as the primary ID/serial ID, I create a ID column and I set it to serial.
I hope this information is helpful to everyone.
*I have no college degree in software development/coding. Everything I know in coding, I study on my own.
Looks like PostgreSQL supports a schema object called a rule.
http://www.postgresql.org/docs/current/static/rules-update.html
You could create a rule ON INSERT for a given table, making it do NOTHING if a row exists with the given primary key value, or else making it do an UPDATE instead of the INSERT if a row exists with the given primary key value.
I haven't tried this myself, so I can't speak from experience or offer an example.
This solution avoids using rules:
BEGIN
INSERT INTO tableA (unique_column,c2,c3) VALUES (1,2,3);
EXCEPTION
WHEN unique_violation THEN
UPDATE tableA SET c2 = 2, c3 = 3 WHERE unique_column = 1;
END;
but it has a performance drawback (see PostgreSQL.org):
A block containing an EXCEPTION clause is significantly more expensive
to enter and exit than a block without one. Therefore, don't use
EXCEPTION without need.
On bulk, you can always delete the row before the insert. A deletion of a row that doesn't exist doesn't cause an error, so its safely skipped.
For data import scripts, to replace "IF NOT EXISTS", in a way, there's a slightly awkward formulation that nevertheless works:
DO
$do$
BEGIN
PERFORM id
FROM whatever_table;
IF NOT FOUND THEN
-- INSERT stuff
END IF;
END
$do$;