1. Search one field
If you want to search one particular field content, using an INDEX and a SELECT will be the fastest.
SELECT * FROM MYTABLE WHERE NAME='Jones';
Do not forget to create an INDEX on the column, first!
2. Fast reading
But if you want to search within a field, or within several fields, you may have to read and check the whole content. In this case, what will be slow will be calling FieldByName()
for each data row: you should better use a local TField
variable.
Or forget about TDataSet
, and switch to direct access to SQLite3. In fact, using DB.pas
and TDataSet
requires a lot of data marshalling, so is slower than a direct access.
See e.g. DiSQLite3 or our DB classes, which are very fast, but a bit of higher level. Or you can use our ORM on top of those classes. Our classes are able to read more than 500,000 rows per second from a SQLite3 database, including JSON marshalling into objects fields.
3. FTS3/FTS4
But, as you guessed, the fastest would be indeed to use the FTS3/FTS4 feature of SQlite3.
You can think of FTS4/FTS4 as a "meta-index" or a "full-text index" on supplied blob of text. Just like google is able to find a word in millions of web pages: it does not use a regular database, but full-text indexing.
In short, you create a virtual FTS3/FTS4 table in your database, then you insert in this table the whole text of your main records in the FTS TEXT field, forcing the ID field to be the one of the original data row.
Then, you will query for some words on your FTS3/FTS4 table, which will give you the matching IDs, much faster than a regular scan.
Note that our ORM has dedicated TSQLRecordFTS3
/ TSQLRecordFTS4
kind of classes for direct FTS process.