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Comment:Add a couple of details to fts5.in.
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SHA1: 23989471bd8f3f7977e146cd0b5dc2691fcd106f
User & Date: dan 2015-03-05 21:00:19
Context
2015-03-06
19:29
Further enhancements to fts5.in. check-in: 984c3483df user: dan tags: trunk
2015-03-05
21:00
Add a couple of details to fts5.in. check-in: 23989471bd user: dan tags: trunk
15:35
Fix the documentation of PRAGMA index_info to omit the three extra files that were reverted. Improve the documentation of PRAGMA index_list to detail the output fields. check-in: 8b3cf7e669 user: drh tags: trunk
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Changes to pages/fts5.in.

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  INSERT INTO ft(ft, rowid, a, b, c) VALUES('delete', 14, $a, $b, $c);
</codeblock>

<p> If the values "inserted" into the text columns as part of a 'delete'
command are not the same as those currently stored within the table, the
results may be unpredictable.

<p><i style=color:red>todo: explain why</i>










<h2 tags="FTS5 delete-all command">The 'delete-all' Command</h2>

<p> This command is only available with [FTS5 external content tables |
external content] and [FTS5 contentless tables | contentless] tables. It
deletes all entries from the full-text index.

................................................................................

<ul>
  <li> Adding new auxiliary functions implemented in C, and
  <li> Adding new tokenizers, also implemented in C.
</ul>

<p> The built-in tokenizers and auxiliary functions described in this
documented are all implemented using the publicly available API described
below.

<p> Before a new auxiliary function or tokenizer implementation may be 
registered with FTS5, an application must obtain a pointer to the "fts5_api"
structure. There is one fts5_api structure for each database connection with
which the FTS5 extension is registered. To obtain the pointer, the application
invokes the SQL user-defined function fts5(), which returns a blob value







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  INSERT INTO ft(ft, rowid, a, b, c) VALUES('delete', 14, $a, $b, $c);
</codeblock>

<p> If the values "inserted" into the text columns as part of a 'delete'
command are not the same as those currently stored within the table, the
results may be unpredictable.

<p> The reason for this is easy to understand: When a document is inserted
into the FTS5 table, an entry is added to the full-text index to record the
position of each token within the new document. When a document is removed,
the original data is required in order to determine the set of entries that
need to be removed from the full-text index. So if the data supplied to FTS5
when a row is deleted using this command is different from that used to
determine the set of token instances when it was inserted, some full-text 
index entries may not be correctly deleted, or FTS5 may try to remove index 
entries that do not exist. This can leave the full-text index in an
unpredictable state, making future query results unreliable.

<h2 tags="FTS5 delete-all command">The 'delete-all' Command</h2>

<p> This command is only available with [FTS5 external content tables |
external content] and [FTS5 contentless tables | contentless] tables. It
deletes all entries from the full-text index.

................................................................................

<ul>
  <li> Adding new auxiliary functions implemented in C, and
  <li> Adding new tokenizers, also implemented in C.
</ul>

<p> The built-in tokenizers and auxiliary functions described in this
document are all implemented using the publicly available API described
below.

<p> Before a new auxiliary function or tokenizer implementation may be 
registered with FTS5, an application must obtain a pointer to the "fts5_api"
structure. There is one fts5_api structure for each database connection with
which the FTS5 extension is registered. To obtain the pointer, the application
invokes the SQL user-defined function fts5(), which returns a blob value