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Overview
Comment: | Documentation updates. Added the "distinctive features" page. (CVS 2383) |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
33a0191638a4d6b33422f62487bfb9a0 |
User & Date: | drh 2005-03-12 15:55:11.000 |
Context
2005-03-12
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18:03 | Fix typo in documentation. (CVS 2384) (check-in: 78012246fc user: drh tags: trunk) | |
15:55 | Documentation updates. Added the "distinctive features" page. (CVS 2383) (check-in: 33a0191638 user: drh tags: trunk) | |
2005-03-11
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18:06 | Version 3.1.5 (CVS 2382) (check-in: b1792ae516 user: drh tags: trunk) | |
Changes
Changes to main.mk.
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417 418 419 420 421 422 423 424 425 426 427 428 429 430 | datatypes.html: $(TOP)/www/datatypes.tcl tclsh $(TOP)/www/datatypes.tcl >datatypes.html datatype3.html: $(TOP)/www/datatype3.tcl tclsh $(TOP)/www/datatype3.tcl >datatype3.html docs.html: $(TOP)/www/docs.tcl tclsh $(TOP)/www/docs.tcl >docs.html download.html: $(TOP)/www/download.tcl mkdir -p doc tclsh $(TOP)/www/download.tcl >download.html | > > > | 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 | datatypes.html: $(TOP)/www/datatypes.tcl tclsh $(TOP)/www/datatypes.tcl >datatypes.html datatype3.html: $(TOP)/www/datatype3.tcl tclsh $(TOP)/www/datatype3.tcl >datatype3.html different.html: $(TOP)/www/different.tcl tclsh $(TOP)/www/different.tcl >different.html docs.html: $(TOP)/www/docs.tcl tclsh $(TOP)/www/docs.tcl >docs.html download.html: $(TOP)/www/download.tcl mkdir -p doc tclsh $(TOP)/www/download.tcl >download.html |
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505 506 507 508 509 510 511 512 513 514 515 516 517 518 | compile.html \ copyright.html \ copyright-release.html \ copyright-release.pdf \ conflict.html \ datatypes.html \ datatype3.html \ docs.html \ download.html \ faq.html \ fileformat.html \ formatchng.html \ index.html \ lang.html \ | > | 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 | compile.html \ copyright.html \ copyright-release.html \ copyright-release.pdf \ conflict.html \ datatypes.html \ datatype3.html \ different.html \ docs.html \ download.html \ faq.html \ fileformat.html \ formatchng.html \ index.html \ lang.html \ |
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Changes to www/different.tcl.
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| | | 1 2 3 4 5 6 7 8 | set rcsid {$Id: different.tcl,v 1.3 2005/03/12 15:55:11 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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77 78 79 80 81 82 83 | the option of writing directly to disk and bypassing the filesystem all together. This provides added performance, but at the cost of considerable setup and maintenance complexity. } feature small {Compact} { When optimized for size, the whole SQLite library with everything enabled | | > > > > > > > > > > > > > > > > > | | > > > > > > > > > > > > > > > > > > > > | > > > > > > > > > > > > > > > > > > > > > > > > > > | < > > > > > | > > > > > > > > > > > > > | 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 | the option of writing directly to disk and bypassing the filesystem all together. This provides added performance, but at the cost of considerable setup and maintenance complexity. } feature small {Compact} { When optimized for size, the whole SQLite library with everything enabled is less than 225KiB in size (as measured on an ix86 using the "size" utility from the GNU compiler suite.) Unneeded features can be disabled at compile-time to further reduce the size of the library to under 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 needed to store the information in a row. If you store a single character in a VARCHAR(100) column, then only a single byte of disk space is consumed. (Actually two bytes - there is some overhead at the beginning of each column to record its datatype and length.) <p> The use of variable-length records by SQLite has a number of advantages. It results in smaller database files, obviously. It also makes the database run faster, since there is less information to move to and from disk. And, the use of variable-length records makes it possible for SQLite to employ manifest typing instead of static typing. } feature readable {Readable source code} { The source code to SQLite is designed to be readable and accessible to the average programmer. All procedures and and data structures and many automatic variables are carefully commented with useful information about what they do. Boilerplate commenting is omitted. } feature vdbe {SQL statements compile into virtual machine code} { Every SQL database engine compiles each SQL statement into some kind of internal data structure which is then used to carry out the work of the statement. But in most SQL engines that internal data structure is a complex web of interlinked structures and objects. In SQLite, the compiled form of statements is a short program in a machine-language like representation. Users of the database can view this <a href="opcode.html">virtual machine language</a> by prepending the <a href="lang_explain.html">EXPLAIN</a> keyword to a query. <p> The use of a virtual machine in SQLite has been a great benefit to library's development. The virtual machine provides a crisp, well-defined junction between the front-end of SQLite (the part that parses SQL statements and generates virtual machine code) and the back-end (the part that executes the virtual machine code and computes a result.) The virtual machine allows the developers to see clearly and in an easily readable form what SQLite is trying to do with each statement it compiles, which is a tremendous help in debuggings. Depending on how it is compiled, SQLite also has the capability of tracing the execution of the virtual machine - printing each virtual machine instruction and its result as it executes. } #feature binding {Tight bindings to dynamic languages} { # Because it is embedded, SQLite can have a much tighter and more natural # binding to high-level dynamic languages such as Tcl, Perl, Python, # PHP, and Ruby. # For example, #} feature license {Public domain} { The source code for SQLite is in the public domain. No claim of copyright is made on any part of the core source code. (The documentation and test code is a different matter - some sections of documentation and test logic are governed by open-sources licenses.) All contributors to the SQLite core software have signed affidavits specifically disavowing any copyright interest in the code. This means that anybody is able to legally do anything they want with the SQLite source code. <p> There are other SQL database engines with liberal licenses that allow the code to be broadly and freely used. But those other engines are still governed by copyright law. SQLite is different in that copyright law simply does not apply. <p> The source code files for other SQL database engines typically begin with a comment describing your license rights to view and copy that file. The SQLite source code contains no license since it is not governed by copyright. Instead of a license, the SQLite source code offers a blessing: <blockquote> <i>May you do good and not evil<br> May you find forgiveness for yourself and forgive others<br> May you share freely, never taking more than you give.</i> </blockquote> } feature extensions {SQL language extensions} { SQLite provides a number of enhancements to the SQL language not normally found in other database engines. The EXPLAIN keyword and manifest typing have already been mentioned above. SQLite also provides statements such as <a href="lang_replace.html">REPLACE</a> and the <a href="lang_conflict.html">ON CONFLICT</a> clause that allow for added control over the resolution of constraint conflicts. SQLite supports <a href="lang_attach.html">ATTACH</a> and <a href="lang_detach.html">DETACH</a> commands that allow multiple independent databases to be used together in the same query. And SQLite defines APIs that allows the user to add new <a href="capi3ref.html#sqlite3_create_function>SQL functions</a> and <a href="capi3ref.html#sqlite3_create_collation>collating sequences</a>. } footer $rcsid |
Changes to www/docs.tcl.
1 2 3 | # This script generates the "docs.html" page that describes various # sources of documentation available for SQLite. # | | | 1 2 3 4 5 6 7 8 9 10 11 | # This script generates the "docs.html" page that describes various # sources of documentation available for SQLite. # set rcsid {$Id: docs.tcl,v 1.10 2005/03/12 15:55:11 drh Exp $} source common.tcl header {SQLite Documentation} puts { <h2>Available Documentation</h2> <table width="100%" cellpadding="5"> } |
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20 21 22 23 24 25 26 27 28 29 30 31 32 33 | } doc {Appropriate Uses For SQLite} {whentouse.html} { This document describes situations where SQLite is an approriate database engine to use versus situations where a client/server database engine might be a better choice. } doc {SQLite In 5 Minutes Or Less} {quickstart.html} { A very quick introduction to programming with SQLite. } doc {SQL Syntax} {lang.html} { This document describes the SQL language that is understood by | > > > > > | 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 | } doc {Appropriate Uses For SQLite} {whentouse.html} { This document describes situations where SQLite is an approriate database engine to use versus situations where a client/server database engine might be a better choice. } doc {Distinctive Features} {different.html} { This document enumerates and describes some of the features of SQLite that make it different from other SQL database engines. } doc {SQLite In 5 Minutes Or Less} {quickstart.html} { A very quick introduction to programming with SQLite. } doc {SQL Syntax} {lang.html} { This document describes the SQL language that is understood by |
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Changes to www/speed.tcl.
1 2 3 | # # Run this Tcl script to generate the speed.html file. # | | | | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | # # Run this Tcl script to generate the speed.html file. # set rcsid {$Id: speed.tcl,v 1.17 2005/03/12 15:55:11 drh Exp $ } source common.tcl header {SQLite Database Speed Comparison} puts { <h2>Database Speed Comparison</h2> <font color="red"><b> Note: This document is old. It describes a speed comparison between an older version of SQLite against archaic versions of MySQL and PostgreSQL. Readers are invited to contribute more up-to-date speed comparisons on the <a href="http://www.sqlite.org/cvstrac/wiki">SQLite Wiki</a>. <p> The numbers here are old enough to be nearly meaningless. Until it is updated, use this document only as proof that SQLite is not a sluggard. </b></font> |
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Changes to www/vdbe.tcl.
1 2 3 | # # Run this Tcl script to generate the vdbe.html file. # | | | > > > > > | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | # # Run this Tcl script to generate the vdbe.html file. # set rcsid {$Id: vdbe.tcl,v 1.14 2005/03/12 15:55:11 drh Exp $} source common.tcl header {The Virtual Database Engine of SQLite} puts { <h2>The Virtual Database Engine of SQLite</h2> <blockquote><b> This document describes the virtual machine used in SQLite version 2.8.0. The virtual machine in SQLite version 3.0 and 3.1 is very similar in concept but many of the opcodes have changed and the algorithms are somewhat different. Use this document as a rough guide to the idea behind the virtual machine in SQLite version 3, not as a reference on how the virtual machine works. </b></blockquote> } puts { <p>If you want to know how the SQLite library works internally, you need to begin with a solid understanding of the Virtual Database Engine or VDBE. The VDBE occurs right in the middle of the |
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