I'm trying to merge tables where rows correspond to a many:1 relationship with "real" things.
I'm writing a blackjack simulator that stores game history in a database with a new set of tables generated each run. The tables are really more like templates, since each game gets its own set of the 3 mutable tables (players, hands, and matches). Here's the layout, where suff is a user-specified suffix to use for the current run:
- cards - id INTEGER PRIMARY KEY - cardValue INTEGER NOT NULL - suit INTEGER NOT NULL - players_suff - whichPlayer INTEGER PRIMARY KEY - aiType TEXT NOT NULL - hands_suff - id BIGSERIAL PRIMARY KEY - whichPlayer INTEGER REFERENCES players_suff(whichPlayer) * - whichHand BIGINT NOT NULL - thisCard INTEGER REFERENCES cards(id) - matches_suff - id BIGSERIAL PRIMARY KEY - whichGame INTEGER NOT NULL - dealersHand BIGINT NOT NULL - whichPlayer INTEGER REFERENCES players_suff(whichPlayer) - thisPlayersHand BIGINT NOT NULL ** - playerResult INTEGER NOT NULL --AKA who won Only one cards table is created because its values are constant.
So after running the simulator twice you might have:
hands_firstrun players_firstrun matches_firstrun hands_secondrun players_secondrun matches_secondrun I want to be able to combine these tables if you used the same AI parameters for both of those runs (i.e. players_firstrun and players_secondrun are exactly the same). The problem is that the way I'm inserting hands makes this really messy: whichHand can't be a BIGSERIAL because the relationship of hands_suff rows to "actual hands" is many:1. matches_suff is handled the same way because a blackjack "game" actually consists of a set of games: the set of pairs of each player vs. the dealer. So for 3 players, you actually have 3 rows for each round.
Currently I select the largest whichHand in the table, add 1 to it, then insert all of the rows for one hand. I'm worried this "query-and-insert" will be really slow if I'm merging 2 tables that might both be arbitrarily huge.
When I'm merging tables, I feel like I should be able to (entirely in SQL) query the largest values in whichHand and whichGame once then use them combine the tables, incrementing them for each unique whichHand and whichGame in the table being merged.
(I saw this question, but it doesn't handle using a generated ID in 2 different places). I'm using Postgres and it's OK if the answer is specific to it.
* sadly postgres doesn't allow parameterized table names so this had to be done by manual string substitution. Not the end of the world since the program isn't web-facing and no one except me is likely to ever bother with it, but the SQL injection vulnerability does not make me happy.
** matches_suff(whichPlayersHand) was originally going to reference hands_suff(whichHand) but foreign keys must reference unique values. whichHand isn't unique because a hand is made up of multiple rows, with each row "holding" one card. To query for a hand you select all of those rows with the same value in whichHand. I couldn't think of a more elegant way to do this without resorting to arrays.
EDIT:
This is what I have now:
thomas=# \dt List of relations Schema | Name | Type | Owner --------+----------------+-------+-------- public | cards | table | thomas public | hands_first | table | thomas public | hands_second | table | thomas public | matches_first | table | thomas public | matches_second | table | thomas public | players_first | table | thomas public | players_second | table | thomas (7 rows) thomas=# SELECT * FROM hands_first thomas-# \g id | whichplayer | whichhand | thiscard ----+-------------+-----------+---------- 1 | 0 | 0 | 6 2 | 0 | 0 | 63 3 | 0 | 0 | 41 4 | 1 | 1 | 76 5 | 1 | 1 | 23 6 | 0 | 2 | 51 7 | 0 | 2 | 29 8 | 0 | 2 | 2 9 | 0 | 2 | 92 10 | 0 | 2 | 6 11 | 1 | 3 | 101 12 | 1 | 3 | 8 (12 rows) thomas=# SELECT * FROM hands_second thomas-# \g id | whichplayer | whichhand | thiscard ----+-------------+-----------+---------- 1 | 0 | 0 | 78 2 | 0 | 0 | 38 3 | 1 | 1 | 24 4 | 1 | 1 | 18 5 | 1 | 1 | 95 6 | 1 | 1 | 40 7 | 0 | 2 | 13 8 | 0 | 2 | 84 9 | 0 | 2 | 41 10 | 1 | 3 | 29 11 | 1 | 3 | 34 12 | 1 | 3 | 56 13 | 1 | 3 | 52 thomas=# SELECT * FROM matches_first thomas-# \g id | whichgame | dealershand | whichplayer | thisplayershand | playerresult ----+-----------+-------------+-------------+-----------------+-------------- 1 | 0 | 0 | 1 | 1 | 1 2 | 1 | 2 | 1 | 3 | 2 (2 rows) thomas=# SELECT * FROM matches_second thomas-# \g id | whichgame | dealershand | whichplayer | thisplayershand | playerresult ----+-----------+-------------+-------------+-----------------+-------------- 1 | 0 | 0 | 1 | 1 | 0 2 | 1 | 2 | 1 | 3 | 2 (2 rows) I'd like to combine them to have:
hands_combined table: id | whichplayer | whichhand | thiscard ----+-------------+-----------+---------- 1 | 0 | 0 | 6 --Seven of Spades 2 | 0 | 0 | 63 --Queen of Spades 3 | 0 | 0 | 41 --Three of Clubs 4 | 1 | 1 | 76 5 | 1 | 1 | 23 6 | 0 | 2 | 51 7 | 0 | 2 | 29 8 | 0 | 2 | 2 9 | 0 | 2 | 92 10 | 0 | 2 | 6 11 | 1 | 3 | 101 12 | 1 | 3 | 8 13 | 0 | 4 | 78 14 | 0 | 4 | 38 15 | 1 | 5 | 24 16 | 1 | 5 | 18 17 | 1 | 5 | 95 18 | 1 | 5 | 40 19 | 0 | 6 | 13 20 | 0 | 6 | 84 21 | 0 | 6 | 41 22 | 1 | 7 | 29 23 | 1 | 7 | 34 24 | 1 | 7 | 56 25 | 1 | 7 | 52 matches_combined table: id | whichgame | dealershand | whichplayer | thisplayershand | playerresult ----+-----------+-------------+-------------+-----------------+-------------- 1 | 0 | 0 | 1 | 1 | 1 2 | 1 | 2 | 1 | 3 | 2 3 | 2 | 4 | 1 | 5 | 0 4 | 3 | 6 | 1 | 7 | 2 Each value of "thiscard" represents a playing card in the range [1..104]--52 playing cards with an extra bit representing if it's face up or face down. I didn't post the actual table for space reasons. So player 0 (aka the dealer) had a hand of (Seven of Spades, Queen of Spaces, 3 of Clubs) in the first game.
4 Answers
Answers 1
Wouldn't using the UNION operator work?
For the hands relation:
SELECT * FROM hands_first UNION ALL SELECT * FROM hands_second For the matches relation:
SELECT * FROM matches_first UNION ALL SELECT * FROM matches_second As a more long term solution I'd consider restructuring the DB because it will quickly become unmanageable with this schema. Why not improve normalization by introducing a games table?
In other words Games have many Matches, matches have many players for each game and players have many hands for each match.
I'd recommend drawing the UML for the entity relationships on paper (http://dawgsquad.googlecode.com/hg/docs/database_images/Database_Model_Diagram(Title).png), then improving the schema so it can be queried using normal SQL operators.
Hope this helps.
EDIT:
In that case you can use a subquery on the union of both tables with the rownumber() PG function to represent the row number:
SELECT row_number() AS id, whichplayer, whichhand, thiscard FROM ( SELECT * FROM hands_first UNION ALL SELECT * FROM hands_second ); The same principle would apply to the matches table. Obviously this doesn't scale well to even a small number of tables, so would prioritize normalizing your schema.
Docs on some PG functions: http://www.postgresql.org/docs/current/interactive/functions-window.html
Answers 2
I think you're not using PostgreSQL the way it's intended to be used, plus your table design may not be suitable for what you want to achieve. Whilst it was difficult to understand what you want your solution to achieve, I wrote this, which seems to solve everything you want using a handful of tables only, and functions that return recordsets for simulating your requirement for individual runs. I used Enums and complex types to illustrate some of the features that you may wish to harness from the power of PostgreSQL.
Also, I'm not sure what parameterized table names are (I have never seen anything like it in any RDBMS), but PostgreSQL does allow something perfectly suitable: recordset returning functions.
CREATE TYPE card_value AS ENUM ('1', '2', '3', '4', '5', '6', '7', '8', '9', '10', 'J', 'Q', 'K'); CREATE TYPE card_suit AS ENUM ('Clubs', 'Diamonds', 'Hearts', 'Spades'); CREATE TYPE card AS (value card_value, suit card_suit, face_up bool); CREATE TABLE runs ( run_id bigserial NOT NULL PRIMARY KEY, run_date timestamptz NOT NULL DEFAULT CURRENT_TIMESTAMP ); CREATE TABLE players ( run_id bigint NOT NULL REFERENCES runs, player_no int NOT NULL, -- 0 can be assumed as always the dealer ai_type text NOT NULL, PRIMARY KEY (run_id, player_no) ); CREATE TABLE matches ( run_id bigint NOT NULL REFERENCES runs, match_no int NOT NULL, PRIMARY KEY (run_id, match_no) ); CREATE TABLE hands ( hand_id bigserial NOT NULL PRIMARY KEY, run_id bigint NOT NULL REFERENCES runs, match_no int NOT NULL, hand_no int NOT NULL, player_no int NOT NULL, UNIQUE (run_id, match_no, hand_no), FOREIGN KEY (run_id, match_no) REFERENCES matches, FOREIGN KEY (run_id, player_no) REFERENCES players ); CREATE TABLE deals ( deal_id bigserial NOT NULL PRIMARY KEY, hand_id bigint NOT NULL REFERENCES hands, card card NOT NULL ); CREATE OR REPLACE FUNCTION players(int) RETURNS SETOF players AS $$ SELECT * FROM players WHERE run_id = $1 ORDER BY player_no; $$ LANGUAGE SQL; CREATE OR REPLACE FUNCTION matches(int) RETURNS SETOF matches AS $$ SELECT * FROM matches WHERE run_id = $1 ORDER BY match_no; $$ LANGUAGE SQL; CREATE OR REPLACE FUNCTION hands(int) RETURNS SETOF hands AS $$ SELECT * FROM hands WHERE run_id = $1 ORDER BY match_no, hand_no; $$ LANGUAGE SQL; CREATE OR REPLACE FUNCTION hands(int, int) RETURNS SETOF hands AS $$ SELECT * FROM hands WHERE run_id = $1 AND match_no = $2 ORDER BY hand_no; $$ LANGUAGE SQL; CREATE OR REPLACE FUNCTION winner_player (int, int) RETURNS int AS $$ SELECT player_no FROM hands WHERE run_id = $1 AND match_no = $2 ORDER BY hand_no DESC LIMIT 1 $$ LANGUAGE SQL; CREATE OR REPLACE FUNCTION next_player_no (int) RETURNS int AS $$ SELECT CASE WHEN EXISTS (SELECT 1 FROM runs WHERE run_id = $1) THEN COALESCE((SELECT MAX(player_no) FROM players WHERE run_id = $1), 0) + 1 END $$ LANGUAGE SQL; CREATE OR REPLACE FUNCTION next_match_no (int) RETURNS int AS $$ SELECT CASE WHEN EXISTS (SELECT 1 FROM runs WHERE run_id = $1) THEN COALESCE((SELECT MAX(match_no) FROM matches WHERE run_id = $1), 0) + 1 END $$ LANGUAGE SQL; CREATE OR REPLACE FUNCTION next_hand_no (int) RETURNS int AS $$ SELECT CASE WHEN EXISTS (SELECT 1 FROM runs WHERE run_id = $1) THEN COALESCE((SELECT MAX(hand_no) + 1 FROM hands WHERE run_id = $1), 0) END $$ LANGUAGE SQL; CREATE OR REPLACE FUNCTION card_to_int (card) RETURNS int AS $$ SELECT ((SELECT enumsortorder::int-1 FROM pg_enum WHERE enumtypid = 'card_suit'::regtype AND enumlabel = ($1).suit::name) * 13 + (SELECT enumsortorder::int-1 FROM pg_enum WHERE enumtypid = 'card_value'::regtype AND enumlabel = ($1).value::name) + 1) * CASE WHEN ($1).face_up THEN 2 ELSE 1 END $$ LANGUAGE SQL; -- SELECT card_to_int(('3', 'Spades', false)) CREATE OR REPLACE FUNCTION int_to_card (int) RETURNS card AS $$ SELECT ((SELECT enumlabel::card_value FROM pg_enum WHERE enumtypid = 'card_value'::regtype AND enumsortorder = ((($1-1)%13)+1)::real), (SELECT enumlabel::card_suit FROM pg_enum WHERE enumtypid = 'card_suit'::regtype AND enumsortorder = (((($1-1)/13)::int%4)+1)::real), $1 > (13*4))::card $$ LANGUAGE SQL; -- SELECT i, int_to_card(i) FROM generate_series(1, 13*4*2) i CREATE OR REPLACE FUNCTION deal_cards(int, int, int, int[]) RETURNS TABLE (player_no int, hand_no int, card card) AS $$ WITH hand AS ( INSERT INTO hands (run_id, match_no, player_no, hand_no) VALUES ($1, $2, $3, next_hand_no($1)) RETURNING hand_id, player_no, hand_no), mydeals AS ( INSERT INTO deals (hand_id, card) SELECT hand_id, int_to_card(card_id)::card AS card FROM hand, UNNEST($4) card_id RETURNING hand_id, deal_id, card ) SELECT h.player_no, h.hand_no, d.card FROM hand h, mydeals d $$ LANGUAGE SQL; CREATE OR REPLACE FUNCTION deals(int) RETURNS TABLE (deal_id bigint, hand_no int, player_no int, card int) AS $$ SELECT d.deal_id, h.hand_no, h.player_no, card_to_int(d.card) FROM hands h JOIN deals d ON (d.hand_id = h.hand_id) WHERE h.run_id = $1 ORDER BY d.deal_id; $$ LANGUAGE SQL; INSERT INTO runs DEFAULT VALUES; -- Add first run INSERT INTO players VALUES (1, 0, 'Dealer'); -- dealer always zero INSERT INTO players VALUES (1, next_player_no(1), 'Player 1'); INSERT INTO matches VALUES (1, next_match_no(1)); -- First match SELECT * FROM deal_cards(1, 1, 0, ARRAY[6, 63, 41]); SELECT * FROM deal_cards(1, 1, 1, ARRAY[76, 23]); SELECT * FROM deal_cards(1, 1, 0, ARRAY[51, 29, 2, 92, 6]); SELECT * FROM deal_cards(1, 1, 1, ARRAY[101, 8]); INSERT INTO matches VALUES (1, next_match_no(1)); -- Second match SELECT * FROM deal_cards(1, 2, 0, ARRAY[78, 38]); SELECT * FROM deal_cards(1, 2, 1, ARRAY[24, 18, 95, 40]); SELECT * FROM deal_cards(1, 2, 0, ARRAY[13, 84, 41]); SELECT * FROM deal_cards(1, 2, 1, ARRAY[29, 34, 56, 52]); SELECT * FROM deals(1); -- This is the output you need (hands_combined table) -- This view can be used to retrieve the list of all winning hands CREATE OR REPLACE VIEW winning_hands AS SELECT DISTINCT ON (run_id, match_no) * FROM hands ORDER BY run_id, match_no, hand_no DESC; SELECT * FROM winning_hands; Answers 3
to build new table with all rows of two tables, do:
CREATE TABLE hands AS select 1 as hand, id, whichplayer, whichhand, thiscard from hands_first union all select 2 as hand, id, whichplayer, whichhand, thiscard from hands_second after that, to insert data of new matche, create sequence with start on current last + 1
CREATE SEQUENCE matche START 3; before insert read sequence value, and use it in inserts:
SELECT nextval('matche'); Answers 4
Your database structure is not great, and I know for sure it is not scalable approach creating tables on fly. There are performance drawbacks creating physical tables instead of using an existing structure. I suggest you refactor your db structure if can.
You can however use the UNION operator to merge your data.
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