SQL · Theory

ngram Fulltext Parser

Theory

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ngram Fulltext Parser

FULLTEXT index lets MATCH (title, body) AGAINST ('exam prep') search words, not LIKE '%exam%'. Needs a FULLTEXT index on those columns (InnoDB in 5.6+).

Natural language mode is default. BOOLEAN MODE uses +must -mustnot. Query expansion is a follow-up search — mention only if asked.

Trap: FULLTEXT on InnoDB with tiny tables (minimum token length, stopwords). Trap: MATCH on columns that are not in the index together.

On the example next to this theory: ngram Fulltext Parser: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Exam tip

MATCH (col) AGAINST ('words') needs a FULLTEXT index.

ngram Fulltext Parser — sample query

-- ngram Fulltext Parser
CREATE TABLE demo (
  id INTEGER PRIMARY KEY,
  label TEXT NOT NULL,
  qty INTEGER DEFAULT 0
);
INSERT INTO demo (id, label, qty) VALUES
  (1, 'alpha', 2),
  (2, 'beta', 5);
SELECT label, qty FROM demo WHERE qty >= 2 ORDER BY qty DESC;

ngram Fulltext Parser: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Short notes

DefFULLTEXT + MATCH … AGAINST for word search.
RuleIndex those columns. InnoDB supported.
TrapLIKE '%word%' instead of MATCH when you already have FULLTEXT.

-- ngram Fulltext Parser CREATE TABLE demo ( id INTEGER PRIMARY KEY, label TEXT NOT NULL, qty INTEGER DEFAULT 0 ); INSERT INTO demo (id, label, qty) VALUES (1, 'alpha', 2), (2, 'beta', 5); SELECT label, qty FROM demo WHERE qty >= 2 ORDER BY qty DESC;

ngram Fulltext Parser

ngram Fulltext Parser — sample query

Short notes

Questions

ngram Fulltext Parser

ngram Fulltext Parser — sample query

Short notes

Questions