From 63847496f14c813a5d80efd5b7de0f1294ffe1e3 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 13 Apr 2024 16:07:11 +0200 Subject: Adding upstream version 3.45.1. Signed-off-by: Daniel Baumann --- www/pgszchng2016.html | 189 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 189 insertions(+) create mode 100644 www/pgszchng2016.html (limited to 'www/pgszchng2016.html') diff --git a/www/pgszchng2016.html b/www/pgszchng2016.html new file mode 100644 index 0000000..f5d6d2a --- /dev/null +++ b/www/pgszchng2016.html @@ -0,0 +1,189 @@ + + + + + +Change in Default Page Size in SQLite Version 3.12.0 + + + +
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+Small. Fast. Reliable.
Choose any three. +
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The Default Page Size Change of SQLite 3.12.0

+ +

1.0 Introduction

+ +

+An SQLite database file consists of one or more "pages". +For a single database file, all pages are the same size, though +for different database files, the page size can any power of +two between 512 and 65536, inclusive. +

+ +

+Since the SQLite database file format was designed (in 2003) the +default page size for new databases has been 1024 bytes. +This was a reasonable choice in 2003. But on modern hardware, +a 4096 byte page is a faster and better choice. +So, beginning with SQLite version 3.12.0 (2016-03-29)) the default +page size for new database files has been increased to 4096 bytes. +

+ +

+The upper bound on the database cache size has +traditionally defaulted to 2000 pages. SQLite version 3.12.0 also +changes this default setting to be "-2000" which means 2000*1024 +bytes, regardless of page size. So, the upper bound on the amount +of memory used for the page cache is unchanged. +

+ +

2.0 Not a Compatibility Break

+ +

+These changes in the default behavior of SQLite are not +a compatibility break. All legacy database files continue to be +readable and writable by newer versions of SQLite, and all newly +created database files continue to be readable and writable by +legacy versions of the SQLite library. The only thing that is changing +is some default settings. This should result in a performance +increase for many applications. +

+ +

+Though most application should not notice any change (except that +they run a little faster), if problems arise then the +legacy behavior can be restored at compile-time by using the +following options to the C-compiler: + +

+-DSQLITE_DEFAULT_PAGE_SIZE=1024 
+-DSQLITE_DEFAULT_CACHE_SIZE=2000
+
+ +

+The page size and cache size can also be set or changed at run-time using the +page_size pragma and cache_size pragma, respectively. + +

3.0 Possible Negative Consequences Of This Change

+ +

+The minimum size of an SQLite database is one page for each table and +each index. With a larger page size, the size of an empty database +for a given schema will grow by a factor of four, therefore. However, +once the database begins to fill with content the size of the older +1024-byte page databases and the newer 4096-byte page databases will +quickly converge. Due to relaxed bin-packing constraints, the +4096-byte page size might actually result in a smaller file, once +substantial content is added. +

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This page last modified on 2022-01-08 05:02:57 UTC

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