Documentation Source Text

Check-in [1225bcc93d]
Login

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:Add a list of shadow tables to the fts5 documentation.
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA3-256:1225bcc93d2bd30726368ce4f1d3eb7e77b1082190cba27ca3eef2aa54d1bd17
User & Date: dan 2018-02-19 10:46:37
Context
2018-02-20
02:53
First cut at a separate document for the printf() string formatters. check-in: 664ed2dce4 user: drh tags: trunk
2018-02-19
10:46
Add a list of shadow tables to the fts5 documentation. check-in: 1225bcc93d user: dan tags: trunk
2018-02-16
14:31
Enhance althttpd.c so that with the -DLOG_HEADER option, it records the complete http request header in logfile-hdr if the "FullHeaderLog" string occurs anyplace in the request path. check-in: b1ce1a2b56 user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to pages/fts5.in.

1934
1935
1936
1937
1938
1939
1940




































       DELETE statement executed by the user. This means that any operation
       on an FTS3/4 table may turn out to be surprisingly slow, as FTS3/4 
       may unpredictably choose to merge together two or more large b-trees
       within it. FTS5 uses incremental merging by default, which limits
       the amount of processing that may take place within any given 
       INSERT, UPDATE or DELETE operation.
</ul>











































>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
       DELETE statement executed by the user. This means that any operation
       on an FTS3/4 table may turn out to be surprisingly slow, as FTS3/4 
       may unpredictably choose to merge together two or more large b-trees
       within it. FTS5 uses incremental merging by default, which limits
       the amount of processing that may take place within any given 
       INSERT, UPDATE or DELETE operation.
</ul>

<h1 id=appendix_b nonumber tags="fts5 shadow tables">
  Appendix B: Shadow tables created by FTS5
</h1>

<p>
When an FTS5 virtual table is created in a database, between 3 and 5 real
tables are created in the database. These are known as "shadow" tables, and are
used by the virtual table module to store persistent data. They should not
be accessed directly by the user. Many other virtual table modules, including
[FTS3] and [rtree], also create and use shadow tables.

<p>FTS5 creates the following shadow tables. In each case the actual table name
is based on the name of the FTS5 virtual table (in the following table, replace
&lt;name&gt; with the name of the virtual table to find the actual shadow
table name).

<table striped=1>
<tr><th>Table&nbsp;Name<th>Contents
<tr><td>&lt;name&gt;_data<td> This table contains most of the full-text index data.
<tr><td>&lt;name&gt;_idx<td> This table contains the remainder of the full-text
index data. It is almost always much smaller than the &lt;name&gt;_data table.
<tr><td>&lt;name&gt;_config<td> Contains the values of persistent
configuration parameters.
<tr><td>&lt;name&gt;_content<td> Contains the actual data inserted into the 
FTS5 table. This shadow table is not present for 
[FTS5 contentless tables | contentless] or 
[FTS5 external content tables|external content] FTS5 tables.
<tr><td>&lt;name&gt;_docsize<td> Contains the size of each column of each
row in the virtual table in tokens. This shadow table is not present if 
the [FTS5 columnsize option|"columnsize" option] is set to 0.
</table>