On Insert: column reference "score" is ambiguous - postgresql

I have the following command in postgresql:
INSERT INTO word_relations(word1_id, word2_id, score) VALUES($1, $2, $3)
ON CONFLICT (word1_id, word2_id) DO UPDATE SET score = score + $3`)
I get the following error:
column reference "score" is ambiguous
I thought it was odd as I am only using one table. Any ideas?


On the right side of the = in the set clause, there are two possibilities for score: EXCLUDED.score and word_relations.score. The former is a way of accessing the value being inserted; the latter a way of accessing the value stored in the row.
I would write this as:
ON CONFLICT (word1_id, word2_id) DO
UPDATE SET score = word_relations.score + EXCLUDED.score

Related

Update column with multiple values Postgres

Sample data:
I am trying update a column with values from multiple columns in another table if two columns match.
Consider the following query:
UPDATE application_table
SET asset_list = asset_table.asset_name
FROM asset_table
WHERE application_table.application_name = asset_table.applications;
My table structure is:
application_table:
"asset_list"; "text[]"
"application_name"; "character varying"
asset_table:
"asset_name"; "character varying"
"applications"; "character varying"
I get the following error:
ERROR: column "asset_list" is of type text[] but expression is of type character varying
Line 12 SET asset_list = asset_table.asset_name

What you need to do is aggregate the asset_name per applications value and set asset_list to that aggregated value.
Problem is you can't do something like
UPDATE ..
SET asset_list = ARRAY_AGG(asset_name)
FROM ...
because aggregate functions are not allowed in updates like that.
So here's two other ways to do it:
UPDATE app_table
SET asset_list = _asset_list
FROM (
SELECT applications, ARRAY_AGG(asset_name ORDER BY asset_name) AS _asset_list
FROM asset_table
GROUP BY applications
) AS a
WHERE app_name = applications;
https://www.db-fiddle.com/f/pKB5k6Lexwzqv6ZbCCdJay/0
This first builds a result set of distinct application names and an array of all the asset_names for each of the app names. Then it updates the table as usual with that array value.
Another way is:
UPDATE app_table
SET asset_list = (SELECT ARRAY_AGG(asset_name ORDER BY asset_name)
FROM asset_table
WHERE applications = app_name)
;
https://www.db-fiddle.com/f/8oVWsubXW93n142gtZYLXB/0
This will update every record in app_table, and calculates the array value on the fly for every record.

Postgres `ON CONFLICT` updates a variable instead of a TABLE, syntax error at or near ""

I created a postgres query that inserts a series of unique codes. If one code is a duplicate I run the following.
ON CONFLICT ON CONSTRAINT uniquecode DO NOTHING;
What I want to do instead of NOTHING is "counter" = "counter" - 1; because within my while loop "counter" is always incremented by 1. If there is a duplicate then I want it reduced so that if I pass in 10 as the number of generated codes, then it will always return 10 unique codes instead of 9 sometimes because one was a duplicate.
However, I receive the following error when I replaceDO NOTHING or NOTHING with the counter reduction.
syntax error at or near "count"
What is this syntax error. All examples I have seen online show table updates instead. Can I simple update a variable instead?
As per the link posted by #a_horse_with_no_name I tried to apply the below after the conflict.
ON CONFLICT ON CONSTRAINT uniquecode DO UPDATE SET "created_at" = NOW();
PERFORM * FROM (
SELECT c."created_at"
FROM "codes" as c
ORDER BY "created_at" DESC
LIMIT 1
) AS "newest";
IF ("newest"::xmax::text::int > 0) THEN
"counter" = "counter" - 1;
END IF;
The intention of the above is that I only reduce the counter if the xmax greater than zero, which means that it was updated not inserted. If updated then that means that "created_at" was changed in the conflict, else do nothing.
Currently, I am at a point where if I keep the PERFORM call then either "type" xmax does not exist or "column" xmax does not exist.

You might use:
ON CONFLICT ON CONSTRAINT uniquecode
DO UPDATE SET count = youtable.column - 1

GET DIAGNOSTICS "found" = ROW_COUNT;
IF ("found" = true) THEN "count" = "count" + 1; END IF;
The above solved my problem. It checks if there was change in the previous code block, if not, then it won't update.

Upsert error (On Conflict Do Update) pointing to duplicate constrained values

I have a problem with ON CONFLICT DO UPDATE in Postgres 9.5 when I try to use more than one source in the FROM statement.
Example of working code:
INSERT INTO new.bookmonographs (citavi_id, abstract, createdon, edition, title, year)
SELECT "ID", "Abstract", "CreatedOn"::timestamp, "Edition", "Title", "Year"
FROM old."Reference"
WHERE old."Reference"."ReferenceType" = 'Book'
AND old."Reference"."Year" IS NOT NULL
AND old."Reference"."Title" IS NOT NULL
ON CONFLICT (citavi_id) DO UPDATE
SET (abstract, createdon, edition, title, year) = (excluded.abstract, excluded.createdon, excluded.edition, excluded.title, excluded.year)
;
Faulty code:
INSERT INTO new.bookmonographs (citavi_id, abstract, createdon, edition, title, year)
SELECT "ID", "Abstract", "CreatedOn"::timestamp, "Edition", "Title", "Year"
FROM old."Reference", old."ReferenceAuthor"
WHERE old."Reference"."ReferenceType" = 'Book'
AND old."Reference"."Year" IS NOT NULL
AND old."Reference"."Title" IS NOT NULL
AND old."ReferenceAuthor"."ReferenceID" = old."Reference"."ID"
--Year, Title and Author must be present in the data, otherwise the entry is deemed useless, hence won't be included
ON CONFLICT (citavi_id) DO UPDATE
SET (abstract, createdon, edition, title, year) = (excluded.abstract, excluded.createdon, excluded.edition, excluded.title, excluded.year)
;
I added an additional source in the FROM statement and one more WHERE statement to make sure only entries that have a title, year and author are inserted into the new database. (If old."Reference"."ID" exists in old."ReferenceAuthor" as "ReferenceID", then an author exists.) Even without the additional WHERE statement the query is faulty. The columns I specified in SELECT are only present in old."Reference", not in old."ReferenceAuthor".
Currently old."ReferenceAuthor" and old."Reference" don't have a UNIQUE CONSTRAINT,the uniqe constraints for bookmonographs are:
CONSTRAINT bookmonographs_pk PRIMARY KEY (bookmonographsid),
CONSTRAINT bookmonographs_bookseries FOREIGN KEY (bookseriesid)
REFERENCES new.bookseries (bookseriesid) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION,
CONSTRAINT bookmonographs_citaviid_unique UNIQUE (citavi_id)
The error PSQL throws:
ERROR: ON CONFLICT DO UPDATE command cannot affect row a second time
HINT: Ensure that no rows proposed for insertion within the same command have duplicate constrained values.
********** Error **********
ERROR: ON CONFLICT DO UPDATE command cannot affect row a second time
SQL state: 21000
Hint: Ensure that no rows proposed for insertion within the same command have duplicate constrained values.
I don't know what's wrong, or why the hint points to a duplicated constrained value.

The problem is caused by the fact that apparently some entries have multiple authors. So the inner join in the select query that you wrote will return multiple rows for the same entry and INSERT ... ON CONFLICT doesn't like that. Since you only use the ReferenceAuthor table for filtering, you can simply rewrite the query so that it uses that table to only filter entries that don't have any author by doing an exists on a correlated subquery. Here's how:
INSERT INTO new.bookmonographs (citavi_id, abstract, createdon, edition, title, year)
SELECT "ID", "Abstract", "CreatedOn"::timestamp, "Edition", "Title", "Year"
FROM old."Reference"
WHERE old."Reference"."ReferenceType" = 'Book'
AND old."Reference"."Year" IS NOT NULL
AND old."Reference"."Title" IS NOT NULL
AND exists(SELECT FROM old."ReferenceAuthor" WHERE old."ReferenceAuthor"."ReferenceID" = old."Reference"."ID")
--Year, Title and Author must be present in the data, otherwise the entry is deemed useless, hence won't be included
ON CONFLICT (citavi_id) DO UPDATE
SET (abstract, createdon, edition, title, year) = (excluded.abstract, excluded.createdon, excluded.edition, excluded.title, excluded.year)
;

Use an explicit INNER JOIN to join the two source tables together:
INSERT INTO new.bookmonographs (citavi_id, abstract, createdon, edition, title, year)
SELECT "ID", "Abstract", "CreatedOn"::timestamp, "Edition", "Title", "Year"
FROM old."Reference"
INNER JOIN old."ReferenceAuthor" -- explicit join
ON old."ReferenceAuthor"."ReferenceID" = old."Reference"."ID" -- ON condition
WHERE old."Reference"."ReferenceType" = 'Book' AND
old."Reference"."Year" IS NOT NULL AND
old."Reference"."Title" IS NOT NULL
ON CONFLICT (citavi_id) DO UPDATE
SET (abstract, createdon, edition, title, year) =
(excluded.abstract, excluded.createdon, excluded.edition, excluded.title,
excluded.year)

There's a great explanation of the issue in postgres' docs (ctrl + f: "Cardinality violation" errors in detail, as there's no direct link).
To quote from the docs:
The idea of raising "cardinality violation" errors is to ensure that any one row is affected no more than once per statement executed. In the lexicon of the SQL standard's discussion of SQL MERGE, the SQL statement is "deterministic". The user ought to be confident that a row will not be affected more than once - if that isn't the case, then it isn't predictable what the final value of a row affected multiple times will be.
To replay their simpler example, on table upsert the below query could not work, as we couldn't reliably know if select val from upsert where key = 1 was equal to 'Foo' or 'Bar':
INSERT INTO upsert(key, val)
VALUES(1, 'Foo'), (1, 'Bar')
ON CONFLICT (key) UPDATE SET val = EXCLUDED.val;
ERROR: 21000: ON CONFLICT UPDATE command could not lock/update self-inserted tuple
HINT: Ensure that no rows proposed for insertion within the same command have duplicate constrained values.

Postgres Update Using Select Passing In Parent Variable

I need to update a few thousand rows in my Postgres table using the result of a array_agg and spatial lookup.
The query needs to take the geometry of the parent table, and return an array of the matching row IDs in the other table. It may return no IDs or potentially 2-3 IDs.
I've tried to use an UPDATE FROM but I can't seem to pass into the subquery the parent table geom column for the SELECT. I can't see any way of doing a JOIN between the 2 tables.
Here is what I currently have:
UPDATE lrc_wales_data.records
SET lrc_array = subquery.lrc_array
FROM (
SELECT array_agg(wales_lrcs.gid) AS lrc_array
FROM layers.wales_lrcs
WHERE st_dwithin(records.geom_poly, wales_lrcs.geom, 0)
) AS subquery
WHERE records.lrc = 'nrw';
The error I get is:
ERROR: invalid reference to FROM-clause entry for table "records"
LINE 7: WHERE st_dwithin(records.geom_poly, wales_lrcs.geom, 0)
Is this even possible?
Many thanks,
Steve

Realised there was no need to use SET FROM. I could just use a sub query directly in the SET:
UPDATE lrc_wales_data.records
SET lrc_array = (
SELECT array_agg(wales_lrcs.gid) AS lrc
FROM layers.wales_lrcs
WHERE st_dwithin(records.geom_poly, wales_lrcs.geom, 0)
)
WHERE records.lrc = 'nrw';

Why can't I use WHERE NOT EXISTS with INSERT?

I want to insert a tag named "foo", unless it already exists. So I constructed the following query:
INSERT INTO "tag" ("name") VALUES ('foo')
WHERE NOT EXISTS (SELECT 1 FROM "tag" WHERE ("tag"."name" = 'foo'));
But this will fail with the following error:
ERROR: syntax error at or near "WHERE"
LINE 1: INSERT INTO "tag" ("name") VALUES ('foo') WHERE NOT EXISTS (...
^
I don't understand where the problem with that query is. Especially, since I can provide a subquery instead of VALUES and suddenly the query is perfectly fine:
INSERT INTO "tag" ("name") SELECT 'foo' AS name
WHERE NOT EXISTS (SELECT 1 FROM "tag" WHERE ("tag"."name" = 'foo'));
This results in:
Query returned successfully: 0 rows affected, 11 ms execution time.
It's 0 rows, because the tag already exists.

You can, you just need to use the INSERT INTO ... SELECT ... form.
INSERT INTO "tag" ("name")
SELECT 'foo'
WHERE NOT EXISTS (SELECT 1 FROM "tag" WHERE ("tag"."name" = 'foo'));
However, it doesn't do what you want. At least not under concurrent workloads. You can still get unique violations or duplicate inserts.
See:
How to UPSERT (MERGE, INSERT ... ON DUPLICATE UPDATE) in PostgreSQL?
Insert, on duplicate update in PostgreSQL?