SAI quickstart

Storage-Attached Indexing (SAI) is an indexing feature that provides a more efficient way to index data in Apache Cassandra®-based tables. SAI is designed to improve query performance by storing index data in the same storage engine as the table data. This feature is particularly useful for tables with large numbers of rows and columns.

Prerequisites:

Install the CQL shell (CQLSH) on your local machine, so that you can run CQL commands on your database.

Create a keyspace

Using cqlsh, define the cycling keyspace:

CREATE KEYSPACE IF NOT EXISTS cycling
WITH REPLICATION = {
  'class' : 'SimpleStrategy',
  'replication_factor' : 1
};

Create a table

Create a cyclist_semi_pro table in the cycling keyspace:

CREATE TABLE IF NOT EXISTS cycling.cyclist_semi_pro (
  id int, 
  firstname text, 
  lastname text, 
  age int, 
  affiliation text,
  country text,
  registration date,
  PRIMARY KEY (id));

Create SAI indexes on the table

To test a non-trivial query, you’ll need some SAI indexes. Use the CREATE CUSTOM INDEX command to create SAI indexes on a few non-primary-key columns in the cyclist_semi_pro table:

CREATE CUSTOM INDEX lastname_idx ON cycling.cyclist_semi_pro (lastname) 
  USING 'StorageAttachedIndex' 
  WITH OPTIONS = {'case_sensitive': 'false', 'normalize': 'true', 'ascii': 'true'}; 
CREATE CUSTOM INDEX age_idx ON cycling.cyclist_semi_pro (age) 
  USING 'StorageAttachedIndex'; 
CREATE CUSTOM INDEX country_idx ON cycling.cyclist_semi_pro (country) 
  USING 'StorageAttachedIndex' 
  WITH OPTIONS = {'case_sensitive': 'false', 'normalize': 'true', 'ascii': 'true'}; 
CREATE CUSTOM INDEX registration_idx ON cycling.cyclist_semi_pro (registration) 
  USING 'StorageAttachedIndex';

Index names are unique per keyspace. The index name must be a unique identifier for the index for each table within a keyspace. Enclose in quotes to use special characters or preserve capitalization. If you do not specify an index name, Hyper-Converged Database (HCD) generates one for you, with the pattern <table_name>_<column_name>_idx. This requirement is true for all indexes.

Let’s take a look at the description of the table and its indexes:

DESCRIBE TABLE cycling.cyclist_semi_pro;

Results

CREATE TABLE cycling.cyclist_semi_pro (
    id int PRIMARY KEY,
    affiliation text,
    age int,
    country text,
    firstname text,
    lastname text,
    registration date
) WITH additional_write_policy = '99p'
    AND bloom_filter_fp_chance = 0.01
    AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'}
    AND cdc = false
    AND comment = ''
    AND compaction = {'class': 'org.apache.cassandra.db.compaction.UnifiedCompactionStrategy'}
    AND compression = {'chunk_length_in_kb': '16', 'class': 'org.apache.cassandra.io.compress.LZ4Compressor'}
    AND memtable = {}
    AND crc_check_chance = 1.0
    AND default_time_to_live = 0
    AND extensions = {}
    AND gc_grace_seconds = 864000
    AND max_index_interval = 2048
    AND memtable_flush_period_in_ms = 0
    AND min_index_interval = 128
    AND read_repair = 'BLOCKING'
    AND speculative_retry = '99p';

Add data to your table

Use INSERT commands to add some data to the cyclist_semi_pro database table:

INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (1, 'Carlos', 'Perotti', 22, 'Recco Club', 'ITA', '2020-01-12'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (2, 'Giovani', 'Pasi', 19, 'Venezia Velocità', 'ITA', '2016-05-15'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (3, 'Frances', 'Giardello', 24, 'Menaggio Campioni', 'ITA', '2018-07-29'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (4, 'Mark', 'Pastore', 19, 'Portofino Ciclisti', 'ITA', '2017-06-16'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (5, 'Irene', 'Cantona', 24, 'Como Velocità', 'ITA', '2012-07-22'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (6, 'Hugo', 'Herrera', 23, 'Bellagio Ciclisti', 'ITA', '2004-02-12');
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (7, 'Marcel', 'Silva', 21, 'Paris Cyclistes', 'FRA', '2018-04-28'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (8, 'Theo', 'Bernat', 19, 'Nice Cavaliers', 'FRA', '2007-05-15'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (9, 'Richie', 'Draxler', 24, 'Normandy Club', 'FRA', '2011-02-26'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (10, 'Agnes', 'Cavani', 22, 'Chamonix Hauteurs', 'FRA', '2020-01-02'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (11, 'Pablo', 'Verratti', 19, 'Chamonix Hauteurs', 'FRA', '2006-05-15'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (12, 'Charles', 'Eppinger', 24, 'Chamonix Hauteurs', 'FRA', '2018-07-29'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (13, 'Stanley', 'Trout', 30, 'Bolder Boulder', 'USA', '2016-02-12'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (14, 'Juan', 'Perez', 31, 'Rutgers Alumni Riders', 'USA', '2017-06-16'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (15, 'Thomas', 'Fulton', 27, 'Exeter Academy', 'USA', '2012-12-15'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (16, 'Jenny', 'Hamler', 28, 'CU Alums Crankworkz', 'USA', '2012-07-22'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (17, 'Alice', 'McCaffrey', 26, 'Pennan Power', 'GBR', '2020-02-12'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (18, 'Nicholas', 'Burrow', 26, 'Aberdeen Association', 'GBR', '2016-02-12'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (19, 'Tyler', 'Higgins', 24, 'Highclere Agents', 'GBR', '2019-07-31'); 
INSERT INTO cycling.cyclist_semi_pro (id, firstname, lastname, age, affiliation, country, registration) VALUES (20, 'Leslie', 'Boyd', 18, 'London Cyclists', 'GBR', '2012-12-15');

Adding data in this quickstart topic shows simple INSERT commands. To load databases with many rows, consider using DataStax Bulk Loader for Cassandra.

Try out CQL queries

Use the CQL SELECT command to submit queries.

The supported query operators for tables with SAI indexes:

Numerics: =, <, >, ⇐, >=, AND, IN, OR (for vector databases)
Strings: =, AND, IN
Collections: = CONTAINS, CONTAINS KEY

The unsupported query operators for tables with SAI indexes:

Strings or Numerics: LIKE, OR (for non-vector databases)

Find a specific semi-pro cyclist:

SELECT * FROM cycling.cyclist_semi_pro
  WHERE lastname = 'Eppinger';

Results

 id | affiliation       | age | country | firstname | lastname | registration
----+-------------------+-----+---------+-----------+----------+--------------
 12 | Chamonix Hauteurs |  24 |     FRA |   Charles | Eppinger |   2018-07-29

(1 rows)

Find semi-pro cyclists whose age is less than or equal to 23:

SELECT * FROM cycling.cyclist_semi_pro WHERE age <= 23;

Results

 id | affiliation        | age | country | firstname | lastname | registration
----+--------------------+-----+---------+-----------+----------+--------------
 10 |  Chamonix Hauteurs |  22 |     FRA |     Agnes |   Cavani |   2020-01-02
 11 |  Chamonix Hauteurs |  19 |     FRA |     Pablo | Verratti |   2006-05-15
  1 |         Recco Club |  22 |     ITA |    Carlos |  Perotti |   2020-01-12
  8 |     Nice Cavaliers |  19 |     FRA |      Theo |   Bernat |   2007-05-15
  2 |   Venezia Velocità |  19 |     ITA |   Giovani |     Pasi |   2016-05-15
  4 | Portofino Ciclisti |  19 |     ITA |      Mark |  Pastore |   2017-06-16
 20 |    London Cyclists |  18 |     GBR |    Leslie |     Boyd |   2012-12-15
  7 |    Paris Cyclistes |  21 |     FRA |    Marcel |    Silva |   2018-04-28
  6 |  Bellagio Ciclisti |  23 |     ITA |      Hugo |  Herrera |   2004-02-12

(9 rows)

Find semi-pro cyclists from Great Britain:

SELECT * FROM cycling.cyclist_semi_pro
  WHERE country = 'GBR';

Results

 id | affiliation          | age | country | firstname | lastname  | registration
----+----------------------+-----+---------+-----------+-----------+--------------
 19 |     Highclere Agents |  24 |     GBR |     Tyler |   Higgins |   2019-07-31
 18 | Aberdeen Association |  26 |     GBR |  Nicholas |    Burrow |   2016-02-12
 20 |      London Cyclists |  18 |     GBR |    Leslie |      Boyd |   2012-12-15
 17 |         Pennan Power |  26 |     GBR |     Alice | McCaffrey |   2020-02-12

(4 rows)

Find semi-pro cyclists who registered between a given date range:

SELECT * FROM cycling.cyclist_semi_pro
  WHERE registration > '2010-01-01' AND registration < '2015-12-31' LIMIT 10;

Results

 id | affiliation         | age | country | firstname | lastname | registration
----+---------------------+-----+---------+-----------+----------+--------------
  5 |       Como Velocità |  24 |     ITA |     Irene |  Cantona |   2012-07-22
 16 | CU Alums Crankworkz |  28 |     USA |     Jenny |   Hamler |   2012-07-22
 15 |      Exeter Academy |  27 |     USA |    Thomas |   Fulton |   2012-12-15
 20 |     London Cyclists |  18 |     GBR |    Leslie |     Boyd |   2012-12-15
  9 |       Normandy Club |  24 |     FRA |    Richie |  Draxler |   2011-02-26

(5 rows)

For query examples with CONTAINS clauses that take advantage of SAI collection maps, lists, and sets, be sure to see SAI collection map examples with keys, values, and entries and SAI collection examples with list and set types.

Removing an SAI index

To remove an SAI index, use DROP INDEX.

Example:

DROP INDEX IF EXISTS cycling.age_sai_idx;

SAI quickstart

Prerequisites:

Create a keyspace

Create a table

Create SAI indexes on the table

Add data to your table

Try out CQL queries

Removing an SAI index

See also

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