Indexing a collection
How to index collections and query the database to find a collection containing a particular value.
Collections can be indexed and queried to find a collection containing a particular value. Sets and lists are indexed a bit differently from maps, given the key-value nature of maps.
Sets and lists can index all values found
by indexing the collection column. Maps can index a map key,
map value, or map entry using the methods shown below. Multiple indexes can be
created on the same map column in a table so that map keys, values, or entries can
be queried. In addition, frozen collections can be indexed using
FULL
to index the full content of a frozen collection.Note: All
the cautions about using
secondary indexes apply to indexing collections.
Procedure
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For set and list collections, create
an index on the column name. Create an index on a set to find all the cyclists
that have been on a particular team.
CREATE INDEX IF NOT EXISTS teams_idx ON cycling.cyclist_career_teams (teams);
SELECT * FROM cycling.cyclist_career_teams WHERE teams CONTAINS 'Rabobank-Liv Giant';
id | lastname | teams --------------------------------------+----------+----------------------------------------------------------------------------- ----------------------- 1c9ebc13-1eab-4ad5-be87-dce433216d40 | BRAND | {'AA Drink - Leontien.nl', 'Leontien.nl', 'Rabobank-Liv Giant', 'Rabobank-Li v Woman Cycling Team'} (1 rows)
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For map collections, create an index on the map key, map
value, or map entry. Create an index on a map key to find
all cyclist/team combinations for a particular year.
CREATE INDEX IF NOT EXISTS team_year_idx ON cycling.cyclist_teams ( KEYS (teams) );
SELECT * FROM cycling.cyclist_teams WHERE teams CONTAINS KEY 2015;
id | firstname | lastname | teams --------------------------------------+-----------+------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- cb07baad-eac8-4f65-b28a-bddc06a0de23 | Elizabeth | ARMITSTEAD | {2011: 'Team Garmin - Cervelo', 2012: 'AA Drink - Leontien.nl', 2013: 'Boels:Dolmans Cycling Team', 2014: 'Boels:Dolmans Cycling Team', 2015: 'Boels:Dolmans Cycling Team'} 5b6962dd-3f90-4c93-8f61-eabfa4a803e2 | Marianne | VOS | {2015: 'Rabobank-Liv Woman Cycling Team'} (2 rows)
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Create an index on the map entries and find cyclists who are the same age. An
index using
ENTRIES
is only valid for maps.CREATE TABLE IF NOT EXISTS cycling.birthday_list ( cyclist_name text PRIMARY KEY, blist map<text, text> );
CREATE INDEX IF NOT EXISTS blist_idx ON cycling.birthday_list ( ENTRIES(blist) );
SELECT * FROM cycling.birthday_list WHERE blist[ 'age' ] = '23';
cyclist_name | blist ------------------+---------------------------------------------------------- Claudio HEINEN | {'age': '23', 'bday': '27/07/1992', 'nation': 'GERMANY'} Laurence BOURQUE | {'age': '23', 'bday': '27/07/1992', 'nation': 'CANADA'} (2 rows)
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Using the same index, find cyclists from the same country.
SELECT * FROM cycling.birthday_list WHERE blist[ 'nation' ] = 'NETHERLANDS';
cyclist_name | blist ---------------+-------------------------------------------------------------- Luc HAGENAARS | {'age': '28', 'bday': '27/07/1987', 'nation': 'NETHERLANDS'} Toine POELS | {'age': '52', 'bday': '27/07/1963', 'nation': 'NETHERLANDS'} (2 rows)
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Create an index on the map values and find cyclists who have a particular value
found in the specified map.
CREATE TABLE IF NOT EXISTS cycling.birthday_list ( cyclist_name text PRIMARY KEY, blist map<text, text> );
CREATE INDEX IF NOT EXISTS blist_values_idx ON cycling.birthday_list ( VALUES(blist) );
SELECT * FROM cycling.birthday_list WHERE blist CONTAINS 'NETHERLANDS';
cyclist_name | blist ---------------+-------------------------------------------------------------- Luc HAGENAARS | {'age': '28', 'bday': '27/07/1987', 'nation': 'NETHERLANDS'} Toine POELS | {'age': '52', 'bday': '27/07/1963', 'nation': 'NETHERLANDS'} (2 rows)
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Create an index on the full content of a
FROZEN
map. The table in this example stores the number of Pro wins, Grand Tour races, and Classic races that a cyclist has competed in. The SELECT statement finds any cyclist who has 39 Pro race wins, 7 Grand Tour starts, and 14 Classic starts.CREATE TABLE IF NOT EXISTS cycling.race_starts ( cyclist_name text PRIMARY KEY, rnumbers FROZEN<LIST<int>> );
CREATE INDEX IF NOT EXISTS rnumbers_idx ON cycling.race_starts ( FULL(rnumbers) );
SELECT * FROM cycling.race_starts WHERE rnumbers = [39, 7, 14];
cyclist_name | rnumbers ----------------+------------- John DEGENKOLB | [39, 7, 14] (1 rows)