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Overview
Comment:Documentation updates. (CVS 2440)
Downloads: Tarball | ZIP archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 7e6f688d468099a6e62e405086c9172459d43e3f
User & Date: drh 2005-04-01 16:29:12.000
Context
2005-04-03
23:54
Apply Tcl 'nullvalue' patch from Stefan Finzel. (CVS 2441) (check-in: 9906ae37b9 user: danielk1977 tags: trunk)
2005-04-01
16:29
Documentation updates. (CVS 2440) (check-in: 7e6f688d46 user: drh tags: trunk)
10:47
Make the ORDER BY clause return equal elements in the same order they were seen (a stable sort). It was returning them in exactly the reverse order. (CVS 2439) (check-in: e8391491a6 user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to www/different.tcl. 
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set rcsid {$Id: different.tcl,v 1.4 2005/03/19 03:41:58 drh Exp $}
source common.tcl
header {Distinctive Features Of SQLite}
puts {
<p>
This page highlights some of the characteristics of SQLite that are
unusual and which make SQLite different from many other SQL
database engines.

|








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set rcsid {$Id: different.tcl,v 1.5 2005/04/01 16:29:12 drh Exp $}
source common.tcl
header {Distinctive Features Of SQLite}
puts {
<p>
This page highlights some of the characteristics of SQLite that are
unusual and which make SQLite different from many other SQL
database engines.
︙︙
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  170KiB if desired.
  <p>
  Most other SQL database engines are much larger than this.  IBM boasts
  that it's recently released CloudScape database engine is "only" a 2MiB
  jar file - 10 times larger than SQLite even after it is compressed!
  Firefox boasts that it's client-side library is only 350KiB.  That's
  50% larger than SQLite and does not even contain the database engine.
  The Berkeley DB library from Sleepycat is 450KiB and it lacks a schema
  layer.
}

feature typing {Manifest typing} {
  Most SQL database engines use static typing.  A datatype is associated
  with each column in a table and only values of that particular datatype
  are allowed to be stored in that column.  SQLite relaxes this restriction
  by using manifest typing.
  In manifest typing, the datatype is a property of the value itself, not 
  of the column in which the value is stored.
  SQLite thus allows the user to store
  any value of any datatype into any column regardless of the declared type
  of that column.  (There are some exceptions to this rule: An INTEGER
  PRIMARY KEY column may only store integers.  And SQLite attempts to coerce
  values into the declared datatype of the column when it can.)
  <p>
  The SQL language specification calls for static typing.  So some people
  feel that the use of manifest typing in SQLite is a bug.  But the authors
  of SQLite feel very strongly that this is a feature.  The authors argue
  that static typing is a bug in the SQL specification that SQLite has fixed
  in a backwards compatible way.
}

feature flex {Variable-length records} {
  Most other SQL database engines allocated a fixed amount of disk space
  for each row in a most tables.  They play special tricks for handling
  BLOBs and CLOBs which can be of wildly varying length.  But for most
  tables, if you declare a column to be a VARCHAR(100) then the database
  engine will allocate
  100 bytes of disk space regardless of how much information you actually
  store in that column.
  <p>
  SQLite, in contrast, use only the amount of disk space actually








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  170KiB if desired.
  <p>
  Most other SQL database engines are much larger than this.  IBM boasts
  that it's recently released CloudScape database engine is "only" a 2MiB
  jar file - 10 times larger than SQLite even after it is compressed!
  Firefox boasts that it's client-side library is only 350KiB.  That's
  50% larger than SQLite and does not even contain the database engine.
  The Berkeley DB library from Sleepycat is 450KiB and it omits SQL
  support, providing the programmer with only simple key/value pairs.
}

feature typing {Manifest typing} {
  Most SQL database engines use static typing.  A datatype is associated
  with each column in a table and only values of that particular datatype
  are allowed to be stored in that column.  SQLite relaxes this restriction
  by using manifest typing.
  In manifest typing, the datatype is a property of the value itself, not 
  of the column in which the value is stored.
  SQLite thus allows the user to store
  any value of any datatype into any column regardless of the declared type
  of that column.  (There are some exceptions to this rule: An INTEGER
  PRIMARY KEY column may only store integers.  And SQLite attempts to coerce
  values into the declared datatype of the column when it can.)
  <p>
  The SQL language specification calls for static typing.  So some people
  feel that the use of manifest typing is a bug in SQLite.  But the authors
  of SQLite feel very strongly that this is a feature.  The authors argue
  that static typing is a bug in the SQL specification that SQLite has fixed
  in a backwards compatible way.
}

feature flex {Variable-length records} {
  Most other SQL database engines allocated a fixed amount of disk space
  for each row in most tables.  They play special tricks for handling
  BLOBs and CLOBs which can be of wildly varying length.  But for most
  tables, if you declare a column to be a VARCHAR(100) then the database
  engine will allocate
  100 bytes of disk space regardless of how much information you actually
  store in that column.
  <p>
  SQLite, in contrast, use only the amount of disk space actually
︙︙