Related
I'm looking for a way to get the list of all json attributes across all my PostgreSQL tables dynamically.
I have Query 1 which would generate a list of sql statements, and then run that sql statements to get the final output all in one go (like the dynamic SQL concept in SQL server).
Query 1 looks like this :
create temporary table test (ordr int, field varchar(1000));
-- Step 1 Create temp table to insert all table/col/json attrbute info
insert into test(ordr,field)
select 0 ordr,'create temporary table temp_table
( table_schema varchar(200)
,table_name varchar(200)
,column_name varchar(200)
,json_attribute varchar(200)
,data_type varchar(50)
);'
union
-- Non json type columns
select 1 ordr, 'insert into temp_table(table_name, column_name,data_type,json_attribute)'
union
-- Json columns with data like json object
select
3 ordr,
concat('select distinct ''', t.table_name, ''' tbl, ''', c.column_name, ''' col, ''' , c.data_type,''' data_type, '
,'jsonb_object_keys(', c.column_name, ') json_attribute', ' from ', t.table_name,
' where jsonb_typeof(' , c.column_name, ') = ''object'' union') AS field
from information_schema.tables t
join information_schema.columns c on c.table_name = t.table_name
where t.table_schema not in ('information_schema', 'pg_catalog')
--and table_type = 'BASE TABLE'
and c.data_type ='jsonb';
--final sql statements to build temp table
--copy all the column "txt" to a separate window and execute it, it will create a temp table "temp_table" which will have all tables/cols/json attributes
select ordr
,(case when t.ordr = (select max(t2.ordr) from test t2) then replace(field,'union','') else field end) txt
from test t
union
select 9999, ';select * from temp_table;'
order by 1 ;
Query 1 output : This is a list of sql statements
I'm looking for a way to run the Query 1 & Query 1 output which would get me the final output all in one go.
Any lead or guidance will be really appreciated.
I'm looking for a way to find the row count for all my tables in Postgres. I know I can do this one table at a time with:
SELECT count(*) FROM table_name;
but I'd like to see the row count for all the tables and then order by that to get an idea of how big all my tables are.
There's three ways to get this sort of count, each with their own tradeoffs.
If you want a true count, you have to execute the SELECT statement like the one you used against each table. This is because PostgreSQL keeps row visibility information in the row itself, not anywhere else, so any accurate count can only be relative to some transaction. You're getting a count of what that transaction sees at the point in time when it executes. You could automate this to run against every table in the database, but you probably don't need that level of accuracy or want to wait that long.
WITH tbl AS
(SELECT table_schema,
TABLE_NAME
FROM information_schema.tables
WHERE TABLE_NAME not like 'pg_%'
AND table_schema in ('public'))
SELECT table_schema,
TABLE_NAME,
(xpath('/row/c/text()', query_to_xml(format('select count(*) as c from %I.%I', table_schema, TABLE_NAME), FALSE, TRUE, '')))[1]::text::int AS rows_n
FROM tbl
ORDER BY rows_n DESC;
The second approach notes that the statistics collector tracks roughly how many rows are "live" (not deleted or obsoleted by later updates) at any time. This value can be off by a bit under heavy activity, but is generally a good estimate:
SELECT schemaname,relname,n_live_tup
FROM pg_stat_user_tables
ORDER BY n_live_tup DESC;
That can also show you how many rows are dead, which is itself an interesting number to monitor.
The third way is to note that the system ANALYZE command, which is executed by the autovacuum process regularly as of PostgreSQL 8.3 to update table statistics, also computes a row estimate. You can grab that one like this:
SELECT
nspname AS schemaname,relname,reltuples
FROM pg_class C
LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace)
WHERE
nspname NOT IN ('pg_catalog', 'information_schema') AND
relkind='r'
ORDER BY reltuples DESC;
Which of these queries is better to use is hard to say. Normally I make that decision based on whether there's more useful information I also want to use inside of pg_class or inside of pg_stat_user_tables. For basic counting purposes just to see how big things are in general, either should be accurate enough.
Here is a solution that does not require functions to get an accurate count for each table:
select table_schema,
table_name,
(xpath('/row/cnt/text()', xml_count))[1]::text::int as row_count
from (
select table_name, table_schema,
query_to_xml(format('select count(*) as cnt from %I.%I', table_schema, table_name), false, true, '') as xml_count
from information_schema.tables
where table_schema = 'public' --<< change here for the schema you want
) t
query_to_xml will run the passed SQL query and return an XML with the result (the row count for that table). The outer xpath() will then extract the count information from that xml and convert it to a number
The derived table is not really necessary, but makes the xpath() a bit easier to understand - otherwise the whole query_to_xml() would need to be passed to the xpath() function.
To get estimates, see Greg Smith's answer.
To get exact counts, the other answers so far are plagued with some issues, some of them serious (see below). Here's a version that's hopefully better:
CREATE FUNCTION rowcount_all(schema_name text default 'public')
RETURNS table(table_name text, cnt bigint) as
$$
declare
table_name text;
begin
for table_name in SELECT c.relname FROM pg_class c
JOIN pg_namespace s ON (c.relnamespace=s.oid)
WHERE c.relkind = 'r' AND s.nspname=schema_name
LOOP
RETURN QUERY EXECUTE format('select cast(%L as text),count(*) from %I.%I',
table_name, schema_name, table_name);
END LOOP;
end
$$ language plpgsql;
It takes a schema name as parameter, or public if no parameter is given.
To work with a specific list of schemas or a list coming from a query without modifying the function, it can be called from within a query like this:
WITH rc(schema_name,tbl) AS (
select s.n,rowcount_all(s.n) from (values ('schema1'),('schema2')) as s(n)
)
SELECT schema_name,(tbl).* FROM rc;
This produces a 3-columns output with the schema, the table and the rows count.
Now here are some issues in the other answers that this function avoids:
Table and schema names shouldn't be injected into executable SQL without being quoted, either with quote_ident or with the more modern format() function with its %I format string. Otherwise some malicious person may name their table tablename;DROP TABLE other_table which is perfectly valid as a table name.
Even without the SQL injection and funny characters problems, table name may exist in variants differing by case. If a table is named ABCD and another one abcd, the SELECT count(*) FROM... must use a quoted name otherwise it will skip ABCD and count abcd twice. The %I of format does this automatically.
information_schema.tables lists custom composite types in addition to tables, even when table_type is 'BASE TABLE' (!). As a consequence, we can't iterate oninformation_schema.tables, otherwise we risk having select count(*) from name_of_composite_type and that would fail. OTOH pg_class where relkind='r' should always work fine.
The type of COUNT() is bigint, not int. Tables with more than 2.15 billion rows may exist (running a count(*) on them is a bad idea, though).
A permanent type need not to be created for a function to return a resultset with several columns. RETURNS TABLE(definition...) is a better alternative.
The hacky, practical answer for people trying to evaluate which Heroku plan they need and can't wait for heroku's slow row counter to refresh:
Basically you want to run \dt in psql, copy the results to your favorite text editor (it will look like this:
public | auth_group | table | axrsosvelhutvw
public | auth_group_permissions | table | axrsosvelhutvw
public | auth_permission | table | axrsosvelhutvw
public | auth_user | table | axrsosvelhutvw
public | auth_user_groups | table | axrsosvelhutvw
public | auth_user_user_permissions | table | axrsosvelhutvw
public | background_task | table | axrsosvelhutvw
public | django_admin_log | table | axrsosvelhutvw
public | django_content_type | table | axrsosvelhutvw
public | django_migrations | table | axrsosvelhutvw
public | django_session | table | axrsosvelhutvw
public | exercises_assignment | table | axrsosvelhutvw
), then run a regex search and replace like this:
^[^|]*\|\s+([^|]*?)\s+\| table \|.*$
to:
select '\1', count(*) from \1 union/g
which will yield you something very similar to this:
select 'auth_group', count(*) from auth_group union
select 'auth_group_permissions', count(*) from auth_group_permissions union
select 'auth_permission', count(*) from auth_permission union
select 'auth_user', count(*) from auth_user union
select 'auth_user_groups', count(*) from auth_user_groups union
select 'auth_user_user_permissions', count(*) from auth_user_user_permissions union
select 'background_task', count(*) from background_task union
select 'django_admin_log', count(*) from django_admin_log union
select 'django_content_type', count(*) from django_content_type union
select 'django_migrations', count(*) from django_migrations union
select 'django_session', count(*) from django_session
;
(You'll need to remove the last union and add the semicolon at the end manually)
Run it in psql and you're done.
?column? | count
--------------------------------+-------
auth_group_permissions | 0
auth_user_user_permissions | 0
django_session | 1306
django_content_type | 17
auth_user_groups | 162
django_admin_log | 9106
django_migrations | 19
[..]
If you don't mind potentially stale data, you can access the same statistics used by the query optimizer.
Something like:
SELECT relname, n_tup_ins - n_tup_del as rowcount FROM pg_stat_all_tables;
Simple Two Steps: (Note : No need to change anything - just copy paste)
1. create function
create function
cnt_rows(schema text, tablename text) returns integer
as
$body$
declare
result integer;
query varchar;
begin
query := 'SELECT count(1) FROM ' || schema || '.' || tablename;
execute query into result;
return result;
end;
$body$
language plpgsql;
2. Run this query to get rows count for all the tables
select sum(cnt_rows) as total_no_of_rows from (select
cnt_rows(table_schema, table_name)
from information_schema.tables
where
table_schema not in ('pg_catalog', 'information_schema')
and table_type='BASE TABLE') as subq;
or
To get rows counts tablewise
select
table_schema,
table_name,
cnt_rows(table_schema, table_name)
from information_schema.tables
where
table_schema not in ('pg_catalog', 'information_schema')
and table_type='BASE TABLE'
order by 3 desc;
Not sure if an answer in bash is acceptable to you, but FWIW...
PGCOMMAND=" psql -h localhost -U fred -d mydb -At -c \"
SELECT table_name
FROM information_schema.tables
WHERE table_type='BASE TABLE'
AND table_schema='public'
\""
TABLENAMES=$(export PGPASSWORD=test; eval "$PGCOMMAND")
for TABLENAME in $TABLENAMES; do
PGCOMMAND=" psql -h localhost -U fred -d mydb -At -c \"
SELECT '$TABLENAME',
count(*)
FROM $TABLENAME
\""
eval "$PGCOMMAND"
done
Extracted from my Comment in the answer from GregSmith to make it more readable:
with tbl as (
SELECT table_schema,table_name
FROM information_schema.tables
WHERE table_name not like 'pg_%' AND table_schema IN ('public')
)
SELECT
table_schema,
table_name,
(xpath('/row/c/text()',
query_to_xml(format('select count(*) AS c from %I.%I', table_schema, table_name),
false,
true,
'')))[1]::text::int AS rows_n
FROM tbl ORDER BY 3 DESC;
Thanks to #a_horse_with_no_name
I usually don't rely on statistics, especially in PostgreSQL.
SELECT table_name, dsql2('select count(*) from '||table_name) as rownum
FROM information_schema.tables
WHERE table_type='BASE TABLE'
AND table_schema='livescreen'
ORDER BY 2 DESC;
CREATE OR REPLACE FUNCTION dsql2(i_text text)
RETURNS int AS
$BODY$
Declare
v_val int;
BEGIN
execute i_text into v_val;
return v_val;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
This worked for me
SELECT schemaname,relname,n_live_tup FROM pg_stat_user_tables ORDER BY
n_live_tup DESC;
I don't remember the URL from where I collected this. But hope this should help you:
CREATE TYPE table_count AS (table_name TEXT, num_rows INTEGER);
CREATE OR REPLACE FUNCTION count_em_all () RETURNS SETOF table_count AS '
DECLARE
the_count RECORD;
t_name RECORD;
r table_count%ROWTYPE;
BEGIN
FOR t_name IN
SELECT
c.relname
FROM
pg_catalog.pg_class c LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
WHERE
c.relkind = ''r''
AND n.nspname = ''public''
ORDER BY 1
LOOP
FOR the_count IN EXECUTE ''SELECT COUNT(*) AS "count" FROM '' || t_name.relname
LOOP
END LOOP;
r.table_name := t_name.relname;
r.num_rows := the_count.count;
RETURN NEXT r;
END LOOP;
RETURN;
END;
' LANGUAGE plpgsql;
Executing select count_em_all(); should get you row count of all your tables.
I made a small variation to include all tables, also for non-public tables.
CREATE TYPE table_count AS (table_schema TEXT,table_name TEXT, num_rows INTEGER);
CREATE OR REPLACE FUNCTION count_em_all () RETURNS SETOF table_count AS '
DECLARE
the_count RECORD;
t_name RECORD;
r table_count%ROWTYPE;
BEGIN
FOR t_name IN
SELECT table_schema,table_name
FROM information_schema.tables
where table_schema !=''pg_catalog''
and table_schema !=''information_schema''
ORDER BY 1,2
LOOP
FOR the_count IN EXECUTE ''SELECT COUNT(*) AS "count" FROM '' || t_name.table_schema||''.''||t_name.table_name
LOOP
END LOOP;
r.table_schema := t_name.table_schema;
r.table_name := t_name.table_name;
r.num_rows := the_count.count;
RETURN NEXT r;
END LOOP;
RETURN;
END;
' LANGUAGE plpgsql;
use select count_em_all(); to call it.
Hope you find this usefull.
Paul
You Can use this query to generate all tablenames with their counts
select ' select '''|| tablename ||''', count(*) from ' || tablename ||'
union' from pg_tables where schemaname='public';
the result from the above query will be
select 'dim_date', count(*) from dim_date union
select 'dim_store', count(*) from dim_store union
select 'dim_product', count(*) from dim_product union
select 'dim_employee', count(*) from dim_employee union
You'll need to remove the last union and add the semicolon at the end !!
select 'dim_date', count(*) from dim_date union
select 'dim_store', count(*) from dim_store union
select 'dim_product', count(*) from dim_product union
select 'dim_employee', count(*) from dim_employee **;**
RUN !!!
Here is a much simpler way.
tables="$(echo '\dt' | psql -U "${PGUSER}" | tail -n +4 | head -n-2 | tr -d ' ' | cut -d '|' -f2)"
for table in $tables; do
printf "%s: %s\n" "$table" "$(echo "SELECT COUNT(*) FROM $table;" | psql -U "${PGUSER}" | tail -n +3 | head -n-2 | tr -d ' ')"
done
output should look like this
auth_group: 0
auth_group_permissions: 0
auth_permission: 36
auth_user: 2
auth_user_groups: 0
auth_user_user_permissions: 0
authtoken_token: 2
django_admin_log: 0
django_content_type: 9
django_migrations: 22
django_session: 0
mydata_table1: 9011
mydata_table2: 3499
you can update the psql -U "${PGUSER}" portion as needed to access your database
note that the head -n-2 syntax may not work in macOS, you could probably just use a different implementation there
Tested on psql (PostgreSQL) 11.2 under CentOS 7
if you want it sorted by table, then just wrap it with sort
for table in $tables; do
printf "%s: %s\n" "$table" "$(echo "SELECT COUNT(*) FROM $table;" | psql -U "${PGUSER}" | tail -n +3 | head -n-2 | tr -d ' ')"
done | sort -k 2,2nr
output;
mydata_table1: 9011
mydata_table2: 3499
auth_permission: 36
django_migrations: 22
django_content_type: 9
authtoken_token: 2
auth_user: 2
auth_group: 0
auth_group_permissions: 0
auth_user_groups: 0
auth_user_user_permissions: 0
django_admin_log: 0
django_session: 0
I like Daniel Vérité's answer.
But when you can't use a CREATE statement you can either use a bash solution or, if you're a windows user, a powershell one:
# You don't need this if you have pgpass.conf
$env:PGPASSWORD = "userpass"
# Get table list
$tables = & 'C:\Program Files\PostgreSQL\9.4\bin\psql.exe' -U user -w -d dbname -At -c "select table_name from information_schema.tables where table_type='BASE TABLE' AND table_schema='schema1'"
foreach ($table in $tables) {
& 'C:\path_to_postresql\bin\psql.exe' -U root -w -d dbname -At -c "select '$table', count(*) from $table"
}
I wanted the total from all tables + a list of tables with their counts. A little like a performance chart of where most time was spent
WITH results AS (
SELECT nspname AS schemaname,relname,reltuples
FROM pg_class C
LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace)
WHERE
nspname NOT IN ('pg_catalog', 'information_schema') AND
relkind='r'
GROUP BY schemaname, relname, reltuples
)
SELECT * FROM results
UNION
SELECT 'all' AS schemaname, 'all' AS relname, SUM(reltuples) AS "reltuples" FROM results
ORDER BY reltuples DESC
You could of course put a LIMIT clause on the results in this version too so that you get the largest n offenders as well as a total.
One thing that should be noted about this is that you need to let it sit for a while after bulk imports. I tested this by just adding 5000 rows to a database across several tables using real import data. It showed 1800 records for about a minute (probably a configurable window)
This is based from https://stackoverflow.com/a/2611745/1548557 work, so thank you and recognition to that for the query to use within the CTE
If you're in the psql shell, using \gexec allows you to execute the syntax described in syed's answer and Aur's answer without manual edits in an external text editor.
with x (y) as (
select
'select count(*), '''||
tablename||
''' as "tablename" from '||
tablename||' '
from pg_tables
where schemaname='public'
)
select
string_agg(y,' union all '||chr(10)) || ' order by tablename'
from x \gexec
Note, string_agg() is used both to delimit union all between statements and to smush the separated datarows into a single unit to be passed into the buffer.
\gexec
Sends the current query buffer to the server, then treats each column of each row of the query's output (if any) as a SQL statement to be executed.
below query will give us row count and size for each table
select table_schema, table_name,
pg_relation_size('"'||table_schema||'"."'||table_name||'"')/1024/1024 size_MB,
(xpath('/row/c/text()', query_to_xml(format('select count(*) AS c from %I.%I', table_schema, table_name),
false, true,'')))[1]::text::int AS rows_n
from information_schema.tables
order by size_MB desc;
I need to create a script to drop and re-create views of a PostgreSQL Database with dependency order
I have tried with this python code:
# Copyleft ....
import os,sys,shutil,re,glob, getopt
import datetime
#import ogr
#open PostGIS connection
import psycopg2
conn = psycopg2.connect(dbname='XXXXX', port=5432, user='XXXXX', password='XXXXXX', host='XXXXXXX')
# Open a cursor to perform database operations
curr = conn.cursor()
conn.autocommit = True
#create the log file
f1=open('./log_cambio_CRS.txt', 'w')
#create the backup SQL file
ora=datetime.datetime.now()
ora_file=ora.strftime("%Y%m%d_%H%M%S")
nomefile='{0}_backup_viste_SIT2017.sql'.format(ora_file)
f2=open(nomefile, 'w')
#select
sql: str = 'SELECT t.table_schema, t.table_name, t.view_definition, row_number() over() as rowid ' \
'FROM information_schema.views t ' \
'where table_schema not in (\'gdo\', \'information_schema\', \'pg_catalog\', \'cron\', \'public\') ' \
'order by rowid desc;'
print(sql)
curr.execute(sql)
for result in curr:
schema=result[0]
table=result[1]
definition=result[2]
f2.write('CREATE OR REPLACE {0}.{1} AS\n {2}'.format(schema,table,definition))
f2.write('\n\n-- **************************************************\n\n')
curr.close
# new query to drop views - the order need to be the reverse
curr = conn.cursor()
#select
sql: str = 'SELECT t.table_schema, t.table_name ' \
'FROM information_schema.views t ' \
'where table_schema not in (\'gdo\', \'information_schema\', \'pg_catalog\', \'cron\',\'public\');'
print(sql)
curr.execute(sql)
for result in curr:
schema=result[0]
table=result[1]
drop_sql='DROP VIEW {0}.{1};'.format(schema,table);
print(drop_sql)
#curr.execute(drop_sql)
curr.close
curr = conn.cursor()
The problem is related to the query
SELECT t.table_schema, t.table_name, t.view_definition, row_number() over() as rowid
FROM information_schema.views t
where table_schema not in ('gdo', 'information_schema', 'pg_catalog', 'cron', 'public')
order by rowid desc;
I'm not sure the order to create the views is correct. For example it is possible that the first view of the SQL depend on a view which is not yet created, so the SQL will not works!
I partially solved (only for DB without restoring) and post the answer for people need the same solution:
The solution is to use the pg_class table which contains the relfilenode field.
The SQL backup script is created ordering the views using the following rule:
order by relfilenode;
while I drop the views ordering them in the opposite way:
order by relfilenode DESC;
An example of query used to obtain the view definitions is the following:
SELECT t.table_schema, t.table_name, t.view_definition,
row_number() over() as rowid , p.relfilenode
FROM information_schema.views t, pg_class p
where table_schema not in ('gdo', 'information_schema', 'pg_catalog', 'cron', 'public')
and p.relname=t.table_name
order by p.relfilenode;
I hope it can be useful, but we need a better solution using pg_depend and/or pg_history
Any examples?
I'm looking for a way to find the row count for all my tables in Postgres. I know I can do this one table at a time with:
SELECT count(*) FROM table_name;
but I'd like to see the row count for all the tables and then order by that to get an idea of how big all my tables are.
There's three ways to get this sort of count, each with their own tradeoffs.
If you want a true count, you have to execute the SELECT statement like the one you used against each table. This is because PostgreSQL keeps row visibility information in the row itself, not anywhere else, so any accurate count can only be relative to some transaction. You're getting a count of what that transaction sees at the point in time when it executes. You could automate this to run against every table in the database, but you probably don't need that level of accuracy or want to wait that long.
WITH tbl AS
(SELECT table_schema,
TABLE_NAME
FROM information_schema.tables
WHERE TABLE_NAME not like 'pg_%'
AND table_schema in ('public'))
SELECT table_schema,
TABLE_NAME,
(xpath('/row/c/text()', query_to_xml(format('select count(*) as c from %I.%I', table_schema, TABLE_NAME), FALSE, TRUE, '')))[1]::text::int AS rows_n
FROM tbl
ORDER BY rows_n DESC;
The second approach notes that the statistics collector tracks roughly how many rows are "live" (not deleted or obsoleted by later updates) at any time. This value can be off by a bit under heavy activity, but is generally a good estimate:
SELECT schemaname,relname,n_live_tup
FROM pg_stat_user_tables
ORDER BY n_live_tup DESC;
That can also show you how many rows are dead, which is itself an interesting number to monitor.
The third way is to note that the system ANALYZE command, which is executed by the autovacuum process regularly as of PostgreSQL 8.3 to update table statistics, also computes a row estimate. You can grab that one like this:
SELECT
nspname AS schemaname,relname,reltuples
FROM pg_class C
LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace)
WHERE
nspname NOT IN ('pg_catalog', 'information_schema') AND
relkind='r'
ORDER BY reltuples DESC;
Which of these queries is better to use is hard to say. Normally I make that decision based on whether there's more useful information I also want to use inside of pg_class or inside of pg_stat_user_tables. For basic counting purposes just to see how big things are in general, either should be accurate enough.
Here is a solution that does not require functions to get an accurate count for each table:
select table_schema,
table_name,
(xpath('/row/cnt/text()', xml_count))[1]::text::int as row_count
from (
select table_name, table_schema,
query_to_xml(format('select count(*) as cnt from %I.%I', table_schema, table_name), false, true, '') as xml_count
from information_schema.tables
where table_schema = 'public' --<< change here for the schema you want
) t
query_to_xml will run the passed SQL query and return an XML with the result (the row count for that table). The outer xpath() will then extract the count information from that xml and convert it to a number
The derived table is not really necessary, but makes the xpath() a bit easier to understand - otherwise the whole query_to_xml() would need to be passed to the xpath() function.
To get estimates, see Greg Smith's answer.
To get exact counts, the other answers so far are plagued with some issues, some of them serious (see below). Here's a version that's hopefully better:
CREATE FUNCTION rowcount_all(schema_name text default 'public')
RETURNS table(table_name text, cnt bigint) as
$$
declare
table_name text;
begin
for table_name in SELECT c.relname FROM pg_class c
JOIN pg_namespace s ON (c.relnamespace=s.oid)
WHERE c.relkind = 'r' AND s.nspname=schema_name
LOOP
RETURN QUERY EXECUTE format('select cast(%L as text),count(*) from %I.%I',
table_name, schema_name, table_name);
END LOOP;
end
$$ language plpgsql;
It takes a schema name as parameter, or public if no parameter is given.
To work with a specific list of schemas or a list coming from a query without modifying the function, it can be called from within a query like this:
WITH rc(schema_name,tbl) AS (
select s.n,rowcount_all(s.n) from (values ('schema1'),('schema2')) as s(n)
)
SELECT schema_name,(tbl).* FROM rc;
This produces a 3-columns output with the schema, the table and the rows count.
Now here are some issues in the other answers that this function avoids:
Table and schema names shouldn't be injected into executable SQL without being quoted, either with quote_ident or with the more modern format() function with its %I format string. Otherwise some malicious person may name their table tablename;DROP TABLE other_table which is perfectly valid as a table name.
Even without the SQL injection and funny characters problems, table name may exist in variants differing by case. If a table is named ABCD and another one abcd, the SELECT count(*) FROM... must use a quoted name otherwise it will skip ABCD and count abcd twice. The %I of format does this automatically.
information_schema.tables lists custom composite types in addition to tables, even when table_type is 'BASE TABLE' (!). As a consequence, we can't iterate oninformation_schema.tables, otherwise we risk having select count(*) from name_of_composite_type and that would fail. OTOH pg_class where relkind='r' should always work fine.
The type of COUNT() is bigint, not int. Tables with more than 2.15 billion rows may exist (running a count(*) on them is a bad idea, though).
A permanent type need not to be created for a function to return a resultset with several columns. RETURNS TABLE(definition...) is a better alternative.
The hacky, practical answer for people trying to evaluate which Heroku plan they need and can't wait for heroku's slow row counter to refresh:
Basically you want to run \dt in psql, copy the results to your favorite text editor (it will look like this:
public | auth_group | table | axrsosvelhutvw
public | auth_group_permissions | table | axrsosvelhutvw
public | auth_permission | table | axrsosvelhutvw
public | auth_user | table | axrsosvelhutvw
public | auth_user_groups | table | axrsosvelhutvw
public | auth_user_user_permissions | table | axrsosvelhutvw
public | background_task | table | axrsosvelhutvw
public | django_admin_log | table | axrsosvelhutvw
public | django_content_type | table | axrsosvelhutvw
public | django_migrations | table | axrsosvelhutvw
public | django_session | table | axrsosvelhutvw
public | exercises_assignment | table | axrsosvelhutvw
), then run a regex search and replace like this:
^[^|]*\|\s+([^|]*?)\s+\| table \|.*$
to:
select '\1', count(*) from \1 union/g
which will yield you something very similar to this:
select 'auth_group', count(*) from auth_group union
select 'auth_group_permissions', count(*) from auth_group_permissions union
select 'auth_permission', count(*) from auth_permission union
select 'auth_user', count(*) from auth_user union
select 'auth_user_groups', count(*) from auth_user_groups union
select 'auth_user_user_permissions', count(*) from auth_user_user_permissions union
select 'background_task', count(*) from background_task union
select 'django_admin_log', count(*) from django_admin_log union
select 'django_content_type', count(*) from django_content_type union
select 'django_migrations', count(*) from django_migrations union
select 'django_session', count(*) from django_session
;
(You'll need to remove the last union and add the semicolon at the end manually)
Run it in psql and you're done.
?column? | count
--------------------------------+-------
auth_group_permissions | 0
auth_user_user_permissions | 0
django_session | 1306
django_content_type | 17
auth_user_groups | 162
django_admin_log | 9106
django_migrations | 19
[..]
If you don't mind potentially stale data, you can access the same statistics used by the query optimizer.
Something like:
SELECT relname, n_tup_ins - n_tup_del as rowcount FROM pg_stat_all_tables;
Simple Two Steps: (Note : No need to change anything - just copy paste)
1. create function
create function
cnt_rows(schema text, tablename text) returns integer
as
$body$
declare
result integer;
query varchar;
begin
query := 'SELECT count(1) FROM ' || schema || '.' || tablename;
execute query into result;
return result;
end;
$body$
language plpgsql;
2. Run this query to get rows count for all the tables
select sum(cnt_rows) as total_no_of_rows from (select
cnt_rows(table_schema, table_name)
from information_schema.tables
where
table_schema not in ('pg_catalog', 'information_schema')
and table_type='BASE TABLE') as subq;
or
To get rows counts tablewise
select
table_schema,
table_name,
cnt_rows(table_schema, table_name)
from information_schema.tables
where
table_schema not in ('pg_catalog', 'information_schema')
and table_type='BASE TABLE'
order by 3 desc;
Not sure if an answer in bash is acceptable to you, but FWIW...
PGCOMMAND=" psql -h localhost -U fred -d mydb -At -c \"
SELECT table_name
FROM information_schema.tables
WHERE table_type='BASE TABLE'
AND table_schema='public'
\""
TABLENAMES=$(export PGPASSWORD=test; eval "$PGCOMMAND")
for TABLENAME in $TABLENAMES; do
PGCOMMAND=" psql -h localhost -U fred -d mydb -At -c \"
SELECT '$TABLENAME',
count(*)
FROM $TABLENAME
\""
eval "$PGCOMMAND"
done
Extracted from my Comment in the answer from GregSmith to make it more readable:
with tbl as (
SELECT table_schema,table_name
FROM information_schema.tables
WHERE table_name not like 'pg_%' AND table_schema IN ('public')
)
SELECT
table_schema,
table_name,
(xpath('/row/c/text()',
query_to_xml(format('select count(*) AS c from %I.%I', table_schema, table_name),
false,
true,
'')))[1]::text::int AS rows_n
FROM tbl ORDER BY 3 DESC;
Thanks to #a_horse_with_no_name
I usually don't rely on statistics, especially in PostgreSQL.
SELECT table_name, dsql2('select count(*) from '||table_name) as rownum
FROM information_schema.tables
WHERE table_type='BASE TABLE'
AND table_schema='livescreen'
ORDER BY 2 DESC;
CREATE OR REPLACE FUNCTION dsql2(i_text text)
RETURNS int AS
$BODY$
Declare
v_val int;
BEGIN
execute i_text into v_val;
return v_val;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
This worked for me
SELECT schemaname,relname,n_live_tup FROM pg_stat_user_tables ORDER BY
n_live_tup DESC;
I don't remember the URL from where I collected this. But hope this should help you:
CREATE TYPE table_count AS (table_name TEXT, num_rows INTEGER);
CREATE OR REPLACE FUNCTION count_em_all () RETURNS SETOF table_count AS '
DECLARE
the_count RECORD;
t_name RECORD;
r table_count%ROWTYPE;
BEGIN
FOR t_name IN
SELECT
c.relname
FROM
pg_catalog.pg_class c LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
WHERE
c.relkind = ''r''
AND n.nspname = ''public''
ORDER BY 1
LOOP
FOR the_count IN EXECUTE ''SELECT COUNT(*) AS "count" FROM '' || t_name.relname
LOOP
END LOOP;
r.table_name := t_name.relname;
r.num_rows := the_count.count;
RETURN NEXT r;
END LOOP;
RETURN;
END;
' LANGUAGE plpgsql;
Executing select count_em_all(); should get you row count of all your tables.
I made a small variation to include all tables, also for non-public tables.
CREATE TYPE table_count AS (table_schema TEXT,table_name TEXT, num_rows INTEGER);
CREATE OR REPLACE FUNCTION count_em_all () RETURNS SETOF table_count AS '
DECLARE
the_count RECORD;
t_name RECORD;
r table_count%ROWTYPE;
BEGIN
FOR t_name IN
SELECT table_schema,table_name
FROM information_schema.tables
where table_schema !=''pg_catalog''
and table_schema !=''information_schema''
ORDER BY 1,2
LOOP
FOR the_count IN EXECUTE ''SELECT COUNT(*) AS "count" FROM '' || t_name.table_schema||''.''||t_name.table_name
LOOP
END LOOP;
r.table_schema := t_name.table_schema;
r.table_name := t_name.table_name;
r.num_rows := the_count.count;
RETURN NEXT r;
END LOOP;
RETURN;
END;
' LANGUAGE plpgsql;
use select count_em_all(); to call it.
Hope you find this usefull.
Paul
You Can use this query to generate all tablenames with their counts
select ' select '''|| tablename ||''', count(*) from ' || tablename ||'
union' from pg_tables where schemaname='public';
the result from the above query will be
select 'dim_date', count(*) from dim_date union
select 'dim_store', count(*) from dim_store union
select 'dim_product', count(*) from dim_product union
select 'dim_employee', count(*) from dim_employee union
You'll need to remove the last union and add the semicolon at the end !!
select 'dim_date', count(*) from dim_date union
select 'dim_store', count(*) from dim_store union
select 'dim_product', count(*) from dim_product union
select 'dim_employee', count(*) from dim_employee **;**
RUN !!!
Here is a much simpler way.
tables="$(echo '\dt' | psql -U "${PGUSER}" | tail -n +4 | head -n-2 | tr -d ' ' | cut -d '|' -f2)"
for table in $tables; do
printf "%s: %s\n" "$table" "$(echo "SELECT COUNT(*) FROM $table;" | psql -U "${PGUSER}" | tail -n +3 | head -n-2 | tr -d ' ')"
done
output should look like this
auth_group: 0
auth_group_permissions: 0
auth_permission: 36
auth_user: 2
auth_user_groups: 0
auth_user_user_permissions: 0
authtoken_token: 2
django_admin_log: 0
django_content_type: 9
django_migrations: 22
django_session: 0
mydata_table1: 9011
mydata_table2: 3499
you can update the psql -U "${PGUSER}" portion as needed to access your database
note that the head -n-2 syntax may not work in macOS, you could probably just use a different implementation there
Tested on psql (PostgreSQL) 11.2 under CentOS 7
if you want it sorted by table, then just wrap it with sort
for table in $tables; do
printf "%s: %s\n" "$table" "$(echo "SELECT COUNT(*) FROM $table;" | psql -U "${PGUSER}" | tail -n +3 | head -n-2 | tr -d ' ')"
done | sort -k 2,2nr
output;
mydata_table1: 9011
mydata_table2: 3499
auth_permission: 36
django_migrations: 22
django_content_type: 9
authtoken_token: 2
auth_user: 2
auth_group: 0
auth_group_permissions: 0
auth_user_groups: 0
auth_user_user_permissions: 0
django_admin_log: 0
django_session: 0
I like Daniel Vérité's answer.
But when you can't use a CREATE statement you can either use a bash solution or, if you're a windows user, a powershell one:
# You don't need this if you have pgpass.conf
$env:PGPASSWORD = "userpass"
# Get table list
$tables = & 'C:\Program Files\PostgreSQL\9.4\bin\psql.exe' -U user -w -d dbname -At -c "select table_name from information_schema.tables where table_type='BASE TABLE' AND table_schema='schema1'"
foreach ($table in $tables) {
& 'C:\path_to_postresql\bin\psql.exe' -U root -w -d dbname -At -c "select '$table', count(*) from $table"
}
I wanted the total from all tables + a list of tables with their counts. A little like a performance chart of where most time was spent
WITH results AS (
SELECT nspname AS schemaname,relname,reltuples
FROM pg_class C
LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace)
WHERE
nspname NOT IN ('pg_catalog', 'information_schema') AND
relkind='r'
GROUP BY schemaname, relname, reltuples
)
SELECT * FROM results
UNION
SELECT 'all' AS schemaname, 'all' AS relname, SUM(reltuples) AS "reltuples" FROM results
ORDER BY reltuples DESC
You could of course put a LIMIT clause on the results in this version too so that you get the largest n offenders as well as a total.
One thing that should be noted about this is that you need to let it sit for a while after bulk imports. I tested this by just adding 5000 rows to a database across several tables using real import data. It showed 1800 records for about a minute (probably a configurable window)
This is based from https://stackoverflow.com/a/2611745/1548557 work, so thank you and recognition to that for the query to use within the CTE
If you're in the psql shell, using \gexec allows you to execute the syntax described in syed's answer and Aur's answer without manual edits in an external text editor.
with x (y) as (
select
'select count(*), '''||
tablename||
''' as "tablename" from '||
tablename||' '
from pg_tables
where schemaname='public'
)
select
string_agg(y,' union all '||chr(10)) || ' order by tablename'
from x \gexec
Note, string_agg() is used both to delimit union all between statements and to smush the separated datarows into a single unit to be passed into the buffer.
\gexec
Sends the current query buffer to the server, then treats each column of each row of the query's output (if any) as a SQL statement to be executed.
below query will give us row count and size for each table
select table_schema, table_name,
pg_relation_size('"'||table_schema||'"."'||table_name||'"')/1024/1024 size_MB,
(xpath('/row/c/text()', query_to_xml(format('select count(*) AS c from %I.%I', table_schema, table_name),
false, true,'')))[1]::text::int AS rows_n
from information_schema.tables
order by size_MB desc;
Hello I am trying to retrieve the schema of an existing table. I am mysql developer and am trying to work with amazon redshift. How can I export the schema of an existing table. In mysql we can use the show create table command.
SHOW CREATE TABLE tblName;
Recently I wrote a python script to clone table schemas between redshift clusters. If you only want the columns and column types of a table, you can do it via:
select column_name,
case
when data_type = 'integer' then 'integer'
when data_type = 'bigint' then 'bigint'
when data_type = 'smallint' then 'smallint'
when data_type = 'text' then 'text'
when data_type = 'date' then 'date'
when data_type = 'real' then 'real'
when data_type = 'boolean' then 'boolean'
when data_type = 'double precision' then 'float8'
when data_type = 'timestamp without time zone' then 'timestamp'
when data_type = 'character' then 'char('||character_maximum_length||')'
when data_type = 'character varying' then 'varchar('||character_maximum_length||')'
when data_type = 'numeric' then 'numeric('||numeric_precision||','||numeric_scale||')'
else 'unknown'
end as data_type,
is_nullable,
column_default
from information_schema.columns
where table_schema = 'xxx' and table_name = 'xxx' order by ordinal_position
;
But if you need the compression types and distkey/sortkeys, you need to query another table:
select * from pg_table_def where tablename = 'xxx' and schemaname='xxx';
This query will give you the complete schema definition including the Redshift specific attributes distribution type/key, sort key, primary key, and column encodings in the form of a create statement as well as providing an alter table statement that sets the owner to the current owner. The only thing it can't tell you are foreign keys. I'm working on the latter, but there's a current privilege issue in RS that prevents us from querying the right tables. This query could use some tuning, but I haven't had time or the need to work it further.
select pk.pkey, tm.schemaname||'.'||tm.tablename, 'create table '||tm.schemaname||'.'||tm.tablename
||' ('
||cp.coldef
-- primary key
||decode(pk.pkey,null,'',pk.pkey)
-- diststyle and dist key
||decode(d.distkey,null,') diststyle '||dist_style||' ',d.distkey)
--sort key
|| (select decode(skey,null,'',skey) from (select
' sortkey(' ||substr(array_to_string(
array( select ','||cast(column_name as varchar(100)) as str from
(select column_name from information_schema.columns col where col.table_schema= tm.schemaname and col.table_name=tm.tablename) c2
join
(-- gives sort cols
select attrelid as tableid, attname as colname, attsortkeyord as sort_col_order from pg_attribute pa where
pa.attnum > 0 AND NOT pa.attisdropped AND pa.attsortkeyord > 0
) st on tm.tableid=st.tableid and c2.column_name=st.colname order by sort_col_order
)
,'')
,2,10000) || ')' as skey
))
||';'
-- additional alter table queries here to set owner
|| 'alter table '||tm.schemaname||'.'||tm.tablename||' owner to "'||tm.owner||'";'
from
-- t master table list
(
SELECT substring(n.nspname,1,100) as schemaname, substring(c.relname,1,100) as tablename, c.oid as tableid ,use2.usename as owner, decode(c.reldiststyle,0,'EVEN',1,'KEY',8,'ALL') as dist_style
FROM pg_namespace n, pg_class c, pg_user use2
WHERE n.oid = c.relnamespace
AND nspname NOT IN ('pg_catalog', 'pg_toast', 'information_schema')
AND c.relname <> 'temp_staging_tables_1'
and c.relowner = use2.usesysid
) tm
-- cp creates the col params for the create string
join
(select
substr(str,(charindex('QQQ',str)+3),(charindex('ZZZ',str))-(charindex('QQQ',str)+3)) as tableid
,substr(replace(replace(str,'ZZZ',''),'QQQ'||substr(str,(charindex('QQQ',str)+3),(charindex('ZZZ',str))-(charindex('QQQ',str)+3)),''),2,10000) as coldef
from
( select array_to_string(array(
SELECT 'QQQ'||cast(t.tableid as varchar(10))||'ZZZ'|| ','||column_name||' '|| decode(udt_name,'bpchar','char',udt_name) || decode(character_maximum_length,null,'', '('||cast(character_maximum_length as varchar(9))||')' )
-- default
|| decode(substr(column_default,2,8),'identity','',null,'',' default '||column_default||' ')
-- nullable
|| decode(is_nullable,'YES',' NULL ','NO',' NOT NULL ')
-- identity
|| decode(substr(column_default,2,8),'identity',' identity('||substr(column_default,(charindex('''',column_default)+1), (length(column_default)-charindex('''',reverse(column_default))-charindex('''',column_default) ) ) ||') ', '')
-- encoding
|| decode(enc,'none','',' encode '||enc)
as str
from
-- ci all the col info
(
select cast(t.tableid as int), cast(table_schema as varchar(100)), cast(table_name as varchar(100)), cast(column_name as varchar(100)),
cast(ordinal_position as int), cast(column_default as varchar(100)), cast(is_nullable as varchar(20)) , cast(udt_name as varchar(50)) ,cast(character_maximum_length as int),
sort_col_order , decode(d.colname,null,0,1) dist_key , e.enc
from
(select * from information_schema.columns c where c.table_schema= t.schemaname and c.table_name=t.tablename) c
left join
(-- gives sort cols
select attrelid as tableid, attname as colname, attsortkeyord as sort_col_order from pg_attribute a where
a.attnum > 0 AND NOT a.attisdropped AND a.attsortkeyord > 0
) s on t.tableid=s.tableid and c.column_name=s.colname
left join
(-- gives encoding
select attrelid as tableid, attname as colname, format_encoding(a.attencodingtype::integer) AS enc from pg_attribute a where
a.attnum > 0 AND NOT a.attisdropped
) e on t.tableid=e.tableid and c.column_name=e.colname
left join
-- gives dist col
(select attrelid as tableid, attname as colname from pg_attribute a where
a.attnum > 0 AND NOT a.attisdropped AND a.attisdistkey = 't'
) d on t.tableid=d.tableid and c.column_name=d.colname
order by ordinal_position
) ci
-- for the working array funct
), '') as str
from
(-- need tableid
SELECT substring(n.nspname,1,100) as schemaname, substring(c.relname,1,100) as tablename, c.oid as tableid
FROM pg_namespace n, pg_class c
WHERE n.oid = c.relnamespace
AND nspname NOT IN ('pg_catalog', 'pg_toast', 'information_schema')
) t
)) cp on tm.tableid=cp.tableid
-- primary key query here
left join
(select c.oid as tableid, ', primary key '|| substring(pg_get_indexdef(indexrelid),charindex('(',pg_get_indexdef(indexrelid))-1 ,60) as pkey
from pg_index i , pg_namespace n, pg_class c
where i.indisprimary=true
and i.indrelid =c.oid
and n.oid = c.relnamespace
) pk on tm.tableid=pk.tableid
-- dist key
left join
( select
-- close off the col defs after the primary key
')' ||
' distkey('|| cast(column_name as varchar(100)) ||')' as distkey, t.tableid
from information_schema.columns c
join
(-- need tableid
SELECT substring(n.nspname,1,100) as schemaname, substring(c.relname,1,100) as tablename, c.oid as tableid
FROM pg_namespace n, pg_class c
WHERE n.oid = c.relnamespace
AND nspname NOT IN ('pg_catalog', 'pg_toast', 'information_schema')
) t on c.table_schema= t.schemaname and c.table_name=t.tablename
join
-- gives dist col
(select attrelid as tableid, attname as colname from pg_attribute a where
a.attnum > 0 AND NOT a.attisdropped AND a.attisdistkey = 't'
) d on t.tableid=d.tableid and c.column_name=d.colname
) d on tm.tableid=d.tableid
where tm.schemaname||'.'||tm.tablename='myschema.mytable'
If you want to get the table structure with create statement, constraints and triggers, you can use pg_dump utility
pg_dump -U user_name -s -t table_name -d db_name
Note: -s used for schema only dump
if you want to take the data only dump , you can use -a switch.
This will output the create syntax with all the constraints. Hope this will help you.
I did not find any complete solutions out there.
And wrote a python script:
https://github.com/cxmcc/redshift_show_create_table
It will work like pg_dump, plus dealing with basic redshift features, SORTKEY/DISTKEY/DISTSTYLES etc.
As show table doesn't work on Redshift:
show table <YOUR_TABLE>;
ERROR: syntax error at or near "<YOUR_TABLE>"
We can use pg_table_def table to get the schema out:
select "column", type, encoding, distkey, sortkey, "notnull"
from pg_table_def
where tablename = '<YOUR_TABLE>';
NOTE: If the schema is not on the search path, add it to search path using:
set search_path to '$user', 'public', '<YOUR_SCHEMA>';
For redshift please try
show table <**tablename**> ;
In Postgres, you'd query the catalog.
From with psql use the shorthands to a variety of commands whose list you'll get by using \? (for help). Therefor, either of:
\d yourtable
\d+ yourtable
For use in an app, you'll need to learn the relevant queries involved. It's relatively straightforward by running psql -E (for echo hidden queries) instead of plain psql.
If you need the precise create table statement, see #Anant answer.
One easy way to do this is to use the utility provided by AWS. All you need to do is to create the view in your database and then query that view to get any table ddl. The advantage to use this view is that it will give you the sortkey and distkey as well which was used in original create table command.
https://github.com/awslabs/amazon-redshift-utils/blob/master/src/AdminViews/v_generate_tbl_ddl.sql
Once the view is created, to get the the ddl of any table. You need to query like this -
select ddl from table where tablename='table_name' and schemaname='schemaname';
Note: Admin schema might not be already there in your cluster. So you can create this view in public schema.
Below query will generate the DDL of the table for you:
SELECT ddl
FROM admin.v_generate_tbl_ddl
WHERE schemaname = '<schemaname>'
AND tablename in (
'<tablename>');
Are you needing to retrieve it programatically or from the psql prompt?
In psql use : \d+ tablename
Programatically, you can query the ANSI standard INFORMATION_SCHEMA views documented here:
http://www.postgresql.org/docs/9.1/static/information-schema.html
The INFORMATION_SCHEMA.TABLES and INFORMATION_SCHEMA.COLUMNS views should have what you need.
You can use admin view provided by AWS Redshift - https://github.com/awslabs/amazon-redshift-utils/blob/master/src/AdminViews/v_generate_tbl_ddl.sql
once you have created the view you can get schema creation script by running:
select * from <db_schema>.v_generate_tbl_ddl where tablename = '<table_name>'
To get the column data and schema of a particular table:
select * from information_schema.columns where tablename='<<table_name>>'
To get the information of a table metadata fire the below query
select * from information_schema.tables where schema='<<schema_name>>'
In the new "query editor 2", you can right click on a table and select "show definition", this will place the DDL for the table in a query window.
The below command will work:
mysql > show create table test.users_info;
Redshift/postgress >pg_dump -U root-w --no-password -h 62.36.11.547 -p 5439 -s -t test.users_info ;