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Diffstat (limited to 'docs/src/schema.dox')
| -rw-r--r-- | docs/src/schema.dox | 37 |
1 files changed, 24 insertions, 13 deletions
diff --git a/docs/src/schema.dox b/docs/src/schema.dox index 5535b47d81c..8f8257239d2 100644 --- a/docs/src/schema.dox +++ b/docs/src/schema.dox @@ -2,13 +2,11 @@ /*! \page schema Schemas -\section schema_intro Tables, Rows and Columns - -XXX rewrite from scratch, fill out with more details about how to use WT_SCHEMA for various things: native C structs, portability between programming languages, non-relational data such as multiple index keys per row, etc. +The tables we have seen so far have all had simple key/value pairs for records. -Lifted from http://en.wikipedia.org/wiki/Column-oriented_DBMS. +\section schema_intro Tables, Rows and Columns -A database program must show its data as two-dimensional tables, of columns and rows, but store it as one-dimensional strings. For example, a database might have this table. +A table is a logical representation of data consisting of cells in rows and columns. For example, a database might have this table. <table> <tr><th>EmpId</th><th>Lastname</th><th>Firstname</th><th>Salary</th></tr> @@ -17,17 +15,17 @@ A database program must show its data as two-dimensional tables, of columns and <tr><td>3</td><td>Johnson</td><td>Cathy</td><td>44000</td></tr> </table> -This simple table includes an employee identifier (EmpId), name fields (Lastname and Firstname) and a salary (Salary). +This simple table includes an employee identifier, last name and first name, and a salary. -A row-oriented database serializes all of the values in a row together, then the values in the next row, and so on: +A row-oriented database would store all of the values in a row together, then the values in the next row, and so on: -<pre>k +<pre> 1,Smith,Joe,40000; 2,Jones,Mary,50000; 3,Johnson,Cathy,44000; </pre> -A column-oriented database serializes all of the values of a column together, then the values of the next column, and so on: +A column-oriented database stores all of the values of a column together, then the values of the next column, and so on: <pre> 1,2,3; @@ -36,11 +34,24 @@ A column-oriented database serializes all of the values of a column together, th 40000,50000,44000; </pre> -\section packing Serializing Values +WiredTiger supports both storage formats, and can mix and match the storage of columns within a logical table. + +Applications describe the format of their data by supplying a *schema* to WT_SESSION::create_table. This specifies how the application's data can be split into fields and mapped onto rows and columns. + +\section schema_columns Describing Columns + +XXX + +\section schema_indices Adding an Index + +XXX + +\section schema_mapping Column Storage -\section schema_storage How Schemas are Stored +XXX -\section schema_startup Loading of Schemas during Startup +\section schema_advanced Advanced Schemas -\section schema_mapping Mapping Tables onto Access Methods +- non-relational data such as multiple index keys per row +- application-supplied extractors and collators may need to be registered before recovery can run. */ |