Recently started working on Postgres and need to pivot data.
I wrote the following query:
select *
from crosstab (
$$
with tmp_kv as (
select distinct pat_id
,col.name as key, replace(replace(replace(value, '[',''), ']', ''),'"','') as value
from (
select p.Id as pat_id, nullif(kv.key,'undefined')::int as key, trim(kv.value::text,'"') as value
from pat_table p
left join e_table e on e.pat_id = p.id and e.id is null
,jsonb_each_text(p.data) as kv
) t
left join lateral (
select name::text as name from public.config_fields fld
where id = t.key
) col on true
)
select pat_id, key, value
from tmp_kv
where nullif(trim(key),'') is not null
order by pat_id, key
$$,$$
select distinct key from tmp_kv -- (Get error "relation "tmp_kv" does not exist" )
where nullif(trim(key),'') is not null
order by 1
$$
) as (
pat_id bigint
...
...
);
Query works if I take the WITH clause out into temporary table. But will be deploying it to production with read replicas, so need it to be working with a CTE. Is there a way?
The two queries passed as strings to the crosstab() function are separate queries.
A CTE can only be attached to a single query.
What you ask for is strictly impossible.
Since you have to spell out the (static) return type for crosstab() anyway, and the result of the query in the 2nd parameter has to match that, it's pointless to use a query with a dynamic result as 2nd parameter to begin with.
I have a view from a query select * from table which returns the below data
I want to group by the name column which have same name and merge the JSONArray column like mentioned below
One way to do this, is to unnest the arrays and then aggregate them back:
select t.id, t.name, jsonb_agg(a.e)
from the_table t
cross join lateral jsonb_array_elements(t.json_array) as a(e)
group by t.id, t.name;
If you do that a lot, a custom aggregate makes this a bit easier to user (but probably not faster)
create function jsonb_array_combine(p_one jsonb, p_two jsonb)
returns jsonb
as
$$
select jsonb_agg(e)
from (
select e
from jsonb_array_elements(p_one) as o(e)
union all
select e
from jsonb_array_elements(p_two) as t(e)
) t
$$
language sql
immutable;
create aggregate jsonb_array_agg(jsonb)
(
SFUNC = jsonb_array_combine(jsonb, jsonb),
STYPE = jsonb
);
Then you can use it like this:
select t.id, t.name, jsonb_array_agg(t.json_array)
from the_table t
group by t.id, t.name;
I have a PostgreSQL function similar to this:
CREATE OR REPLACE FUNCTION dbo.MyTestFunction(
_ID INT
)
RETURNS dbo.MyTable AS
$$
SELECT *,
(SELECT Name FROM dbo.MySecondTable WHERE RecordID = PersonID)
FROM dbo.MyTable
WHERE PersonID = _ID
$$ LANGUAGE SQL STABLE;
I would really like to NOT have to replace the RETURNS dbo.MyTable AS with something like:
RETURNS TABLE(
col1 INT,
col2 TEXT,
col3 BOOLEAN,
col4 TEXT
) AS
and list out all the columns of MyTable and Name of MySecondTable. Is this something that can be done? Thanks.
--EDIT--
To clarify I have to return ALL columns in MyTable and 1 column from MySecondTable. If MyTable has >15 columns, I don't want to have to list out all the columns in a RETURNS TABLE (col1.. coln).
You just list the columns that you want returned in the SELECT portion of your SQL statement:
SELECT t1.column1, t1.column2,
(SELECT Name FROM dbo.MySecondTable WHERE RecordID = PersonID)
FROM dbo.MyTable t1
WHERE PersonID = _ID
Now you'll just get column1, column3, and name returned
Furthermore, you'll probably find better performance using a LEFT OUTER JOIN in your FROM portion of the SQL statement as opposed to the correlated subquery you have now:
SELECT t1.column1, t1.column2, t2.Name
FROM dbo.MyTable t1
LEFT OUTER JOIN dbo.MySecondTable t2 ON
t2.RecordID = t1.PersonID
WHERE PersonID = _ID
Took a bit of a guess on where RecordID and PersonID were coming from, but that's the general idea.
Using Postgres 9.4, I am looking for a way to merge two (or more) json or jsonb columns in a query. Consider the following table as an example:
id | json1 | json2
----------------------------------------
1 | {'a':'b'} | {'c':'d'}
2 | {'a1':'b2'} | {'f':{'g' : 'h'}}
Is it possible to have the query return the following:
id | json
----------------------------------------
1 | {'a':'b', 'c':'d'}
2 | {'a1':'b2', 'f':{'g' : 'h'}}
Unfortunately, I can't define a function as described here. Is this possible with a "traditional" query?
In Postgres 9.5+ you can merge JSONB like this:
select json1 || json2;
Or, if it's JSON, coerce to JSONB if necessary:
select json1::jsonb || json2::jsonb;
Or:
select COALESCE(json1::jsonb||json2::jsonb, json1::jsonb, json2::jsonb);
(Otherwise, any null value in json1 or json2 returns an empty row)
For example:
select data || '{"foo":"bar"}'::jsonb from photos limit 1;
?column?
----------------------------------------------------------------------
{"foo": "bar", "preview_url": "https://unsplash.it/500/720/123"}
Kudos to #MattZukowski for pointing this out in a comment.
Here is the complete list of build-in functions that can be used to create json objects in PostgreSQL. http://www.postgresql.org/docs/9.4/static/functions-json.html
row_to_json and json_object doest not allow you to define your own keys, so it can't be used here
json_build_object expect you to know by advance how many keys and values our object will have, that's the case in your example, but should not be the case in the real world
json_object looks like a good tool to tackle this problem but it forces us to cast our values to text so we can't use this one either
Well... ok, wo we can't use any classic functions.
Let's take a look at some aggregate functions and hope for the best... http://www.postgresql.org/docs/9.4/static/functions-aggregate.html
json_object_agg Is the only aggregate function that build objects, that's our only chance to tackle this problem. The trick here is to find the correct way to feed the json_object_agg function.
Here is my test table and data
CREATE TABLE test (
id SERIAL PRIMARY KEY,
json1 JSONB,
json2 JSONB
);
INSERT INTO test (json1, json2) VALUES
('{"a":"b", "c":"d"}', '{"e":"f"}'),
('{"a1":"b2"}', '{"f":{"g" : "h"}}');
And after some trials and errors with json_object here is a query you can use to merge json1 and json2 in PostgreSQL 9.4
WITH all_json_key_value AS (
SELECT id, t1.key, t1.value FROM test, jsonb_each(json1) as t1
UNION
SELECT id, t1.key, t1.value FROM test, jsonb_each(json2) as t1
)
SELECT id, json_object_agg(key, value)
FROM all_json_key_value
GROUP BY id
For PostgreSQL 9.5+, look at Zubin's answer.
This function would merge nested json objects
create or replace function jsonb_merge(CurrentData jsonb,newData jsonb)
returns jsonb
language sql
immutable
as $jsonb_merge_func$
select case jsonb_typeof(CurrentData)
when 'object' then case jsonb_typeof(newData)
when 'object' then (
select jsonb_object_agg(k, case
when e2.v is null then e1.v
when e1.v is null then e2.v
when e1.v = e2.v then e1.v
else jsonb_merge(e1.v, e2.v)
end)
from jsonb_each(CurrentData) e1(k, v)
full join jsonb_each(newData) e2(k, v) using (k)
)
else newData
end
when 'array' then CurrentData || newData
else newData
end
$jsonb_merge_func$;
Looks like nobody proposed this kind of solution yet, so here's my take, using custom aggregate functions:
create or replace aggregate jsonb_merge_agg(jsonb)
(
sfunc = jsonb_concat,
stype = jsonb,
initcond = '{}'
);
create or replace function jsonb_concat(a jsonb, b jsonb) returns jsonb
as 'select $1 || $2'
language sql
immutable
parallel safe
;
Note: this is using || which replaces existing values at same path instead of deeply merging them.
Now jsonb_merge_agg is accessible like so:
select jsonb_merge_agg(some_col) from some_table group by something;
Also you can tranform json into text, concatenate, replace and convert back to json. Using the same data from Clément you can do:
SELECT replace(
(json1::text || json2::text),
'}{',
', ')::json
FROM test
You could also concatenate all json1 into single json with:
SELECT regexp_replace(
array_agg((json1))::text,
'}"(,)"{|\\| |^{"|"}$',
'\1',
'g'
)::json
FROM test
This is a very old solution, since 9.4 you should use json_object_agg and simple || concatenate operator. Keeping here just for reference.
However this question is answered already some time ago; the fact that when json1 and json2 contain the same key; the key appears twice in the document, does not seem to be best practice.
Therefore u can use this jsonb_merge function with PostgreSQL 9.5:
CREATE OR REPLACE FUNCTION jsonb_merge(jsonb1 JSONB, jsonb2 JSONB)
RETURNS JSONB AS $$
DECLARE
result JSONB;
v RECORD;
BEGIN
result = (
SELECT json_object_agg(KEY,value)
FROM
(SELECT jsonb_object_keys(jsonb1) AS KEY,
1::int AS jsb,
jsonb1 -> jsonb_object_keys(jsonb1) AS value
UNION SELECT jsonb_object_keys(jsonb2) AS KEY,
2::int AS jsb,
jsonb2 -> jsonb_object_keys(jsonb2) AS value ) AS t1
);
RETURN result;
END;
$$ LANGUAGE plpgsql;
The following query returns the concatenated jsonb columns, where the keys in json2 are dominant over the keys in json1:
select id, jsonb_merge(json1, json2) from test
FYI, if someone's using jsonb in >= 9.5 and they only care about top-level elements being merged without duplicate keys, then it's as easy as using the || operator:
select '{"a1": "b2"}'::jsonb || '{"f":{"g" : "h"}}'::jsonb;
?column?
-----------------------------
{"a1": "b2", "f": {"g": "h"}}
(1 row)
Try this, if anyone having an issue for merging two JSON object
select table.attributes::jsonb || json_build_object('foo',1,'bar',2)::jsonb FROM table where table.x='y';
CREATE OR REPLACE FUNCTION jsonb_merge(pCurrentData jsonb, pMergeData jsonb, pExcludeKeys text[])
RETURNS jsonb IMMUTABLE LANGUAGE sql
AS $$
SELECT json_object_agg(key,value)::jsonb
FROM (
WITH to_merge AS (
SELECT * FROM jsonb_each(pMergeData)
)
SELECT *
FROM jsonb_each(pCurrentData)
WHERE key NOT IN (SELECT key FROM to_merge)
AND ( pExcludeKeys ISNULL OR key <> ALL(pExcludeKeys))
UNION ALL
SELECT * FROM to_merge
) t;
$$;
SELECT jsonb_merge('{"a": 1, "b": 9, "c": 3, "e":5}'::jsonb, '{"b": 2, "d": 4}'::jsonb, '{"c","e"}'::text[]) as jsonb
works well as an alternative to || when recursive deep merge is required (found here) :
create or replace function jsonb_merge_recurse(orig jsonb, delta jsonb)
returns jsonb language sql as $$
select
jsonb_object_agg(
coalesce(keyOrig, keyDelta),
case
when valOrig isnull then valDelta
when valDelta isnull then valOrig
when (jsonb_typeof(valOrig) <> 'object' or jsonb_typeof(valDelta) <> 'object') then valDelta
else jsonb_merge_recurse(valOrig, valDelta)
end
)
from jsonb_each(orig) e1(keyOrig, valOrig)
full join jsonb_each(delta) e2(keyDelta, valDelta) on keyOrig = keyDelta
$$;
I'm trying to get array_agg to work with an array type in Postgresql and I'm having trouble figuring out if this is possible and if so how to do it. The pertinent part of my query looks like this:
array_agg(ARRAY[e.alert_type::text, e.id::text, cast(extract(epoch from e.date_happened) as text)] order by e.date_happened asc, e.id asc)
The error that I'm getting in response is ERROR: could not find array type for data type text[]
Is this possible or should I try to find another approach?
Thanks!
You could write custom aggregate to handle your specific array of arrays, e.g.:
DROP TABLE IF EXISTS e;
CREATE TABLE e
(
id serial PRIMARY KEY,
alert_type text,
date_happened timestamp with time zone
);
INSERT INTO e(alert_type, date_happened) VALUES
('red', '2011-05-10 10:15:06'),
('yellow', '2011-06-22 20:01:19');
CREATE OR REPLACE FUNCTION array_agg_custom_cut(anyarray)
RETURNS anyarray
AS 'SELECT $1[2:array_length($1, 1)]'
LANGUAGE SQL IMMUTABLE;
DROP AGGREGATE IF EXISTS array_agg_custom(anyarray);
CREATE AGGREGATE array_agg_custom(anyarray)
(
SFUNC = array_cat,
STYPE = anyarray,
FINALFUNC = array_agg_custom_cut,
INITCOND = $${{'', '', ''}}$$
);
Query:
SELECT
array_agg_custom(
ARRAY[
alert_type::text,
id::text,
CAST(extract(epoch FROM date_happened) AS text)
])
FROM e;
Result:
array_agg_custom
--------------------------------------------
{{red,1,1305036906},{yellow,2,1308787279}}
(1 row)
EDIT:
Here is second, shorter way (that is, you don't need array_agg_custom_cut function, but as you see additional ARRAY level is necessary in query):
CREATE AGGREGATE array_agg_custom(anyarray)
(
SFUNC = array_cat,
STYPE = anyarray
);
SELECT
array_agg_custom(
ARRAY[
ARRAY[
alert_type::text,
id::text,
CAST(extract(epoch FROM date_happened) AS text)
]
])
FROM e;
Result:
array_agg_custom
--------------------------------------------
{{red,1,1305036906},{yellow,2,1308787279}}
(1 row)
or cast the array to text like array_agg(array[xxx, yyy]::text)
array_agg(ARRAY[e.alert_type::text, e.id::text,
cast(extract(epoch from e.date_happened) as text)]::text
order by e.date_happened asc, e.id asc)