postgresql-performance

I have been trying to find an optimal solution to select unique values from each column . My problem is I don't know column names in advance since different table has different number of columns. So first, I have to find column names and I could use below query to do it: select column_name from information_schema.columns where table_name='m0301010000_ds' and column_name like 'c%' Sample output for column names: c1, c2a, c2b, c2c, c2d, c2e, c2f, c2g, c2h, c2i, c2j, c2k, ... Then I would use returned column names to get unique/distinct value in each column and not just distinct row . I know a

I've got a PostgreSQL table called queries_query , which has many columns. Two of these columns, created and user_sid , are frequently used together in SQL queries by my application to determine how many queries a given user has done over the past 30 days. It is very, very rare that I query these stats for any time older than the most recent 30 days. Here is my question: I've currently created my multi-column index on these two columns by running: CREATE INDEX CONCURRENTLY some_index_name ON queries_query (user_sid, created) But I'd like to further restrict the index to only care about those

Why is the table "events_201504" included in the query plan below? Based on my query and the check constraint on that table I would expect the query planner to be able to prune it entirely: database=# \d events_201504 Table "public.events_201504" Column | Type | Modifiers ---------------+-----------------------------+--------------------------------------------------------------- id | bigint | not null default nextval('events_id_seq'::regclass) created_at | timestamp without time zone | Indexes: "events_201504_pkey" PRIMARY KEY, btree (id) "events_201504_created_at" btree (created_at) Check

I currently have the following: User (id, fname, lname, deleted_at, guest) I can query for a list of user's by their fname initial like so: User Load (9.6ms) SELECT "users".* FROM "users" WHERE (users.deleted_at IS NULL) AND (lower(left(fname, 1)) = 's') ORDER BY fname ASC LIMIT 25 OFFSET 0 This is fast thanks to the following index: CREATE INDEX users_multi_idx ON users (lower(left(fname, 1)), fname) WHERE deleted_at IS NULL; What I want to do now is be able to query for all Users that do not start with the letter's A-Z. I got this to work like so: SELECT "users".* FROM "users" WHERE (users

I am running the following query: SELECT fat.* FROM Table1 fat LEFT JOIN modo_captura mc ON mc.id = fat.modo_captura_id INNER JOIN loja lj ON lj.id = fat.loja_id INNER JOIN rede rd ON rd.id = fat.rede_id INNER JOIN bandeira bd ON bd.id = fat.bandeira_id INNER JOIN produto pd ON pd.id = fat.produto_id INNER JOIN loja_extensao le ON le.id = fat.loja_extensao_id INNER JOIN conta ct ON ct.id = fat.conta_id INNER JOIN banco bc ON bc.id = ct.banco_id LEFT JOIN conciliacao_vendas cv ON fat.empresa_id = cv.empresa_id AND cv.chavefato = fat.chavefato AND fat.rede_id = cv.rede_id WHERE 1 = 1 AND cv