The document discusses the implementation of full-text search in databases, highlighting its advantages over traditional text searching methods due to specific challenges encountered. It details examples using PostgreSQL, covering performance issues and accuracy problems with standard SQL queries. Full-text search in PostgreSQL utilizes the 'tsvector' and 'tsquery' for effective text representation and search predicates, enhancing search speed and accuracy.

1. Implementasi Full Text
Search pada Database
24 November 2020
dipersiapkan oleh Dony Riyanto

2. Text Searching
• Pencarian text pada database memiliki permasalahan khusus
• Dibutuhkan solusi pencarian text yang lebih baik
• Full text search adalah salah satu solusinya

3. Sampledata
• StackOverflow.com Posts
• Data dumpexported September
2009
• 1.2million tuples
• ~850 MB

4. StackOverflowERdiagram

5. Performanceissue
• LIKEwith wildcards: SELECT*
FROMPosts
WHEREbody LIKE ‘%postgresql%’
• POSIXregular expressions:
SELECT* FROMPosts WHERE
body ~ ‘postgresql’
time:91 sec
time:105 sec

6. Why so slow?
CREA
TET
ABLEtelephone_book
( full_nameVARCHAR(50) );
CREA
TEINDEX name_idxON telephone_book
(full_name);
INSERTINTO telephone_book V
ALUES
(‘Riddle,Thomas’),
(‘Thomas,Dean’);

7. Why so slow?
SELECT* FROMtelephone_book
WHEREfull_nameLIKE ‘Thomas%’
• Searchfor allwith lastname“Thomas”
• Searchfor allwith first name“Thomas”
SELECT* FROMtelephone_book WHERE
full_nameLIKE ‘%Thomas’

8. Accuracyissue
• Irrelevant or falsematching words
‘one’,‘money’,‘prone’,etc.:
body LIKE‘%one%’
• Regularexpressionsin PostgreSQL
support escapesfor word boundaries:
body ~ ‘yoney’

9. FullTextSearch

10. PostgreSQLText-Search
• SincePostgreSQL8.3
• TSVECTORto represent textdata
• TSQUERYto represent searchpredicates
• Special indexes

11. PostgreSQLT
ext-Search:
BasicQuerying
SELECT* FROMPosts
WHEREto_tsvector(title || ‘ ’ || body || ‘ ’ || tags)
@@ to_tsquery(‘postgresql & performance’);
text-search matching
operator

12. PostgreSQLT
ext-Search:
BasicQuerying
SELECT* FROMPosts
WHEREtitle || ‘ ’ || body || ‘ ’ || tags
@@ ‘postgresql &performance’;
timewithnoindex:8min2 s
e
c

13. PostgreSQLT
ext-Search:
AddTSVECTORcolumn
AL
TERT
ABLEPostsADDCOLUMN
PostTextTSVECTOR;
UPDATEPostsSETPostText= to_tsvector(‘english’,
title || ‘ ’ || body ||‘ ’ || tags);