 Generating test data for full text search tests

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Updates / Generating test data for full text search tests by

Ciro Santilli 36  Updated 2025-04-24  +Created 2024-12-23

I've been thinking lightly about adding full text search to OurBigBook.

For example, at docs.ourbigbook.com/news/article-and-topic-id-prefix-search article search was added, but it only finds if you search something that appears right at the start of a title, e.g. for:

Fundamental theorem of calculus

you'd get a hit for:

fundamental

but not for

calculus

To do this efficiently, we need full text search, which PostgreSQL implements.

But finding a clean way to generate test data for testing out the speedup was not so easy and exploration into this led me to publishing a few new slightly improved methods where Googlers can now find them:

unix.stackexchange.com/questions/97160/is-there-something-like-a-lorem-ipsum-generator/787733#787733 I propose a neat random "sentence" generator using common CLI tools like grep and sed and the pre-installed Ubuntu dictionary /usr/share/dict/american-english:
```
grep -v "'" /usr/share/dict/american-english |
shuf -r |
paste -d ' ' $(printf "%4s" | sed 's/ /- /g') |
sed -e 's/^$.$/\U\1/;s/$/./' |
head -n10000000 \
> lorem.txt
```
- to achieve that, I also proposed two superior "join every N lines" method for the CLI: stackoverflow.com/questions/25973140/joining-every-group-of-n-lines-into-one-with-bash/79257780#79257780, notably this awk poem:
  seq 10 | awk '{ printf("%s%s", NR == 1 ? "" : NR % 3 == 1 ? "\n" : " ", $0 ) } END { printf("\n") }'

stackoverflow.com/questions/3371503/sql-populate-table-with-random-data/79255281#79255281 I propose:

a clean PostgreSQL random string stored procedure that picks random characters from an allowed character list

CREATE OR REPLACE FUNCTION random_string(int) RETURNS TEXT as $$
select
string_agg(substr(characters, (random() * length(characters) + 1)::integer, 1), '') as random_word
from (values('ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-    ')) as symbols(characters)
join generate_series(1, $1) on 1 = 1
$$ language sql;

first generating PostgreSQL data as CSV, and then importing the CSV into PostgreSQL as a more flexible method. This can also be done in a streaming fashion from stdin which is neat.
```
python generate_data.py 10 | psql mydb -c '\copy "mytable" FROM STDIN'
```

stackoverflow.com/questions/16020164/psqlexception-error-syntax-error-in-tsquery/79437030#79437030 regarding the safe generation of prefix search tsquery from user inputs without query errors, I've learned about websearch_to_tsquery and further highlighted a possible tsquery -> text -> tsquery approach that might be correct for prefix searches
stackoverflow.com/questions/67438575/fulltext-search-using-sequelize-postgres/79439253#79439253 I put everything together into a minimal Sequelize example, read for usage in OurBigBook

Finally I did a writeup summarizing PostgreSQL full text search: Section "PostgreSQL full-text search" and also dumped it at: www.reddit.com/r/PostgreSQL/comments/12yld1o/is_it_worth_using_postgres_builtin_fulltext/ for good measure.

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