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Last modified by christoph_lechleitner@iteg_at on 2013-01-31 07.32:56
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1 1  = {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Preliminary"/}}Preliminary =
2 2  
3 -The SchemaManager and SchemaEngine give you an abstracted access to the database schema of your application, allowing you to add and delete tables, columns, relations and data in the database on application updates. It uses a designated table to keep track of the current schema status, which it will check whenever it is run, and update the database if it is not at the correct version.
3 +The SchemaManager ({{code language="none"}}org.clazzes.jdbc2xml.schema.SchemaManager{{/code}}) and SchemaEngine provide means to maintain the database scheme of an application, allowing you to add and delete tables, columns, relations and data in the database along application updates.
4 4  
5 -SchemaManager ({{code language="none"}}org.clazzes.jdbc2xml.schema.SchemaManager{{/code}}) will create a table called SCHEMA_HISTORY if it can not find it the first time it is run. This table contains the following columns:
5 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-SchemaHistoryTable"/}}Schema History Table ===
6 6  
7 -{{code language="none"}}
8 -VERSION:varchar(10), not null, primary key
9 -DESCRIPTION:varchar(512), nullable
10 -CREATION_DATE:date, nullable
11 -SERIALNR:integer(5), not null
12 -{{/code}}
7 +A designated schema table, by default named SCHEMA_HISTORY, is used to keep track of the current scheme. It will be automatically at SchemaManager's first run. (% style="font-size: 10.0pt;line-height: 13.0pt;" %)SCHEMA_HISTORY contains the following columns:
13 13  
9 +|=(((
10 +
11 +)))|=(((
12 +
13 +)))
14 +|(((
15 +(% class="code" %)
16 +(((
17 +VERSION
18 +)))
19 +)))|(((
20 +(% class="code" %)
21 +(((
22 +varchar(10), not null, primary key
23 +)))
24 +)))
25 +|(((
26 +(% class="code" %)
27 +(((
28 +DESCRIPTION
29 +)))
30 +)))|(((
31 +(% class="code" %)
32 +(((
33 +varchar(512), nullable
34 +)))
35 +)))
36 +|(((
37 +(% class="code" %)
38 +(((
39 +CREATION_DATE
40 +)))
41 +)))|(((
42 +(% class="code" %)
43 +(((
44 +date, nullable
45 +)))
46 +)))
47 +|(((
48 +(% class="code" %)
49 +(((
50 +SERIALNR
51 +)))
52 +)))|(((
53 +(% class="code" %)
54 +(((
55 +integer(5), not null
56 +)))
57 +)))
58 +
59 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-CustomnameforSchemaHistoryTable"/}}Custom name for Schema History Table ===
60 +
61 +(% style="font-size: 10.0pt;line-height: 13.0pt;" %)In (% style="font-size: 10.0pt;font-weight: normal;line-height: 13.0pt;" %)heterogenous environments as well as in heavily modularized software architectures a single database may be shared by multiple parties each requiring a couple of tables.
62 +
63 +(% style="font-size: 10.0pt;font-weight: normal;line-height: 13.0pt;" %)To allow multiple modules (applications, libraries, other OSGi bundles) to use (% style="font-size: 10.0pt;line-height: 13.0pt;" %)JDBC2XML's SchemaManager concurrently within one database, as of JDBC 1.1.1 SchemaManager hold the name of the schema history table in an overwritable property, {{code language="none"}}versionHistoryTable{{/code}}. See (%%)[[JDBCTOXML-11>>url:https://jira.clazzes.org/browse/JDBCTOXML-11||shape="rect"]](% style="font-size: 10.0pt;line-height: 13.0pt;" %).
64 +
14 14  = {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-ProjectConfiguration"/}}Project Configuration =
15 15  
16 -To function correctly, SchemaManager needs a DataSource ({{code language="none"}}javax.sql.DataSource{{/code}}) and a list of TableInfo ({{code language="none"}}org.clazzes.jdbc2xml.schema.TableInfo{{/code}}) Objects, from which a database will be created if it finds an empty database. To function properly, it also needs an implementation of ISchemaEngine ({{code language="none"}}org.clazzes.jdbc2xml.schema.ISchemaEngine{{/code}}).
67 +SchemaManager requires a DataSource ({{code language="none"}}javax.sql.DataSource{{/code}}) and a list of TableInfo ({{code language="none"}}org.clazzes.jdbc2xml.schema.TableInfo{{/code}}) Objects, from which database structures will be created if an "empty" database is detected. Furthermore, an implementation of ISchemaEngine ({{code language="none"}}org.clazzes.jdbc2xml.schema.ISchemaEngine{{/code}}) is required.
17 17  
18 -Optionally, you may set the base version (default value 0.1.00) and base description String (default "initial database schema").
69 +Optionally, a base version (default value 0.1.00) and a base description String (default "initial database schema") may be specified.
19 19  
20 20  Database updates are passed as a Map<String, ISchemaUpdateSnippet> (org.clazzes.jdbc2xml.schema.ISchemaUpdateSnippet) - details see below.
21 21  
22 22  To perform the operations, call {{code language="none"}}SchemaManager.start(){{/code}}.
23 23  
24 -=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-UsingSpringorOSGi/Blueprint"/}}Using Spring or OSGi/Blueprint ===
75 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-ConfigurationusingSpringorOSGi/Blueprint"/}}Configuration using Spring or OSGi/Blueprint ===
25 25  
26 26  If you are using OSGi with Blueprint or Spring to set up your project, you can configure a SchemaManager instance by adding the following to your blueprint {{code language="none"}}services.xml{{/code}} (or Spring configuration file):
27 27  
... ... @@ -33,7 +33,7 @@
33 33  </bp:reference>
34 34   
35 35  <bp:bean id="sqlDialect" factory-ref="dialectFactory" factory-method="newDialect">
36 -<bp:argument> <!-- Pass JDBC URL as an argument -->
87 +<bp:argument ref="jdbcUrl"><!-- bean jdbcUrl specified above -->
37 37  </bp:argument>
38 38  </bp:bean>
39 39   
... ... @@ -45,22 +45,35 @@
45 45  <bp:bean id="databaseSetup" class="org.clazzes.jdbc2xml.schema.SchemaManager" init-method="start">
46 46  <bp:property name="dataSource" ref="dataSource"></bp:property>
47 47  <bp:property name="schemaEngine" ref="schemaEngine"></bp:property>
99 + <!-- optional but recommended: special name for schema history table: -->
100 + <bp:property name="versionHistoryTable" value="MYLIB_SCHEMA_HISTORY"/>
101 + <!-- optional but recommended: explicit first version -->
48 48  <bp:property name="baseVersion" value="0.1.00" />
49 49  <bp:property name="baseTables">
50 -<!-- Add List of TableDefinitions here (see below) -->
104 +<!-- List of TableDefinitions here (see below), typical: -->
105 + <!-- <bp:bean factory-ref="tableDefinitions" factory-method="getSetup" /> -->
51 51  </bp:property>
107 + <!-- Add Update-Snippets here, example for updates from 0.1.00 to 0.1.01 and on to 0.2.00
52 52  <bp:property name="upateSnippets">
53 -<!-- Add Update-Snippets here -->
109 +<bp:map>
110 + <bp:entry key="0.1.00" value="foo.schema.SchemaUpdate_0_1_01"></bp:entry>
111 + <bp:entry key="0.1.01" value="foo.schema.SchemaUpdate_0_2_00"></bp:entry>
112 +</bp:map>
54 54  </bp:property>
114 + -->
55 55  </bp:bean>
56 56  {{/code}}
57 57  
58 -By default, JDBC2XML provides an implementation of IDialectFactory and ISchemaEngineFactory as an OSGi service or via ServiceRegistry lookup for Spring.
118 +By default, JDBC2XML provides an implementation of IDialectFactory and ISchemaEngineFactory as an OSGi service or via ServiceRegistry for Spring.
59 59  
60 60  = {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Settingupaninitialdatabaseschema"/}}Setting up an initial database schema =
61 61  
62 -To create an initial database schema, you will need to provide SchemaManager with a list of TableInfo objects. The recommended way to do this is to provide a class in your project which creates this list in it's constructor and provides it through a getter. You can instantiate this class in your Spring/Blueprint config as a singleton, and feed the provided List to SchemaManager. An example of this class could look like this:
122 +To create an initial database schema, SchemaManager needs a list of TableInfo objects.
63 63  
124 +The recommended strategy is to create an InitialSchema class providing this list through a getter.
125 +
126 +(% style="font-size: 10.0pt;line-height: 13.0pt;" %)This is an example:
127 +
64 64  {{code language="java"}}
65 65  package org.clazzes.example.jdbc2xml;
66 66  
... ... @@ -73,28 +73,19 @@
73 73  import org.clazzes.jdbc2xml.schema.PrimaryKeyInfo;
74 74  import org.clazzes.jdbc2xml.schema.TableInfo;
75 75   
76 -public class TableDefinitions {
140 +public class InitialSchema {
77 77  
78 - // It is adviseable to provide the Strings used as names for tables and columns as constants, so they can be reused outside this object to build sql-statements
79 - public static final String TB_EXAMPLE_TABLE_NAME = "ADDRESSBOOK";
80 - public static final String COL_EXAMPLE_ID = "ID";
81 - public static final String COL_EXAMPLE_NAME = "NAME";
82 - public static final String COL_EXAMPLE_ADDRESS_REF = "ADDRESS";
83 - public static final String COL_EXAMPLE_BIRTHDAY = "BIRTHDAY";
84 - 
85 - // ...
86 - 
87 87   private List<TableInfo> setup;
88 88  
89 89   public TableDefinitions() {
90 90  // Create a table
91 -TableInfo exampleTable = new TableInfo(TB_EXAMPLE_TABLE_NAME);
146 +TableInfo exampleTable = new TableInfo(TableDefs.TB_EXAMPLE_TABLE_NAME);
92 92  exampleTable.setColumns(
93 93   Arrays.asList(new ColumnInfo[] {
94 -new ColumnInfo(COL_EXAMPLE_ID, Types.BIGINT, 20, null, false, null,true),
95 -new ColumnInfo(COL_EXAMPLE_NAME, Types.VARCHAR, 256, null, false, null),
96 -new ColumnInfo(COL_EXAMPLE_ADDRESS_REF, Types.BIGINT, 20, null, true, null),
97 -new ColumnInfo(COL_EXAMPLE_BIRTHDAY, Types.DATE, 12, null, false, null)
149 +new ColumnInfo(TableDefs.COL_EXAMPLE_ID, Types.BIGINT, 20, null, false, null,true),
150 +new ColumnInfo(TableDefs.COL_EXAMPLE_NAME, Types.VARCHAR, 256, null, false, null),
151 +new ColumnInfo(TableDefs.COL_EXAMPLE_ADDRESS_REF, Types.BIGINT, 20, null, true, null),
152 +new ColumnInfo(TableDefs.COL_EXAMPLE_BIRTHDAY, Types.DATE, 12, null, false, null)
98 98  }));
99 99   
100 100  // Example for creating a foreign key reference
... ... @@ -116,13 +116,42 @@
116 116  
117 117   }
118 118    
119 - public List<TableInfo> getSetup() {
120 -return this.setup;
174 + public List<TableInfo> getSchema() {
175 +return this.schema;
121 121   }
122 122  
123 123  }
124 124  {{/code}}
125 125  
181 +{{code language="java"}}
182 +package org.clazzes.example.jdbc2xml;
183 +
184 +import java.sql.Types;
185 +import java.util.Arrays;
186 +import java.util.List;
187 +
188 +import org.clazzes.jdbc2xml.schema.ColumnInfo;
189 +import org.clazzes.jdbc2xml.schema.ForeignKeyInfo;
190 +import org.clazzes.jdbc2xml.schema.PrimaryKeyInfo;
191 +import org.clazzes.jdbc2xml.schema.TableInfo;
192 +
193 +public class TableDefs {
194 +
195 + // It is adviseable to provide the Strings used as names for tables and columns as constants,
196 + // so they can be reused savely to construct SQL statements
197 + public static final String TABLENAME_ADDRESSBOOK = "ADDRESSBOOK";
198 + public static final String COL_ADDRESSBOOK_ID = "ID";
199 + public static final String COL_ADDRESSBOOK_NAME = "NAME";
200 + public static final String COL_ADDRESSBOOK_ADDRESS_REF = "ADDRESS";
201 + public static final String COL_ADDRESSBOOK_BIRTHDAY = "BIRTHDAY";
202 +
203 +}
204 +{{/code}}
205 +
206 +
207 +
208 +
209 +
126 126  You must inject {{code language="none"}}TableDefinitions.getSetup(){{/code}} into {{code language="none"}}SchemaManager.setBaseTables(){{/code}} before calling {{code language="none"}}SchemaManager.start(){{/code}}.
127 127  
128 128  Using Blueprint/Spring, you can do this by inserting the following snippet in the bean definition for SchemaManager:
... ... @@ -230,10 +230,50 @@
230 230  <!-- ... and continues here -->
231 231  {{/code}}
232 232  
233 -
317 += {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-SchemaMaintainanceStrategies"/}}Schema Maintainance Strategies =
234 234  
235 -
319 +The JDBC2XML Schema management tools allow for 2 different strategies:
236 236  
321 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Frozen(Initial)TableList"/}}Frozen (% style="font-size: 14.0pt;" %)(Initial) Table List(%%) ===
322 +
323 +The legacy strategy is:
324 +
325 +(% style="list-style-type: square;" %)
326 +* At the start of a project, create and use TableDefinitions.java
327 +* After the first commit, TableDefinitions are considered frozen, all changes go into SchemaUpdates, up to one update per source code commit
328 +
329 +Advantage: Rock solid.
330 +
331 +Disadvantage: No place to look for the complete current scheme, except actual databases. See //Recommendation 1// below for a workaround.
332 +
333 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Possiblebutdangerous:Evolving(Initial)TableList"/}}Possible but dangerous: Evolving (Initial) Table List ===
334 +
335 +To keep the TableDefinitions up do date, one might use this strategy:
336 +
337 +(% style="list-style-type: square;" %)
338 +* keep the TableDefinitions up to date, so an empty database always gets the current scheme in one shot
339 +* SchemaUpdates are only applied to existing databases
340 +
341 +Advantage: Immediate overview over current scheme.
342 +
343 +Disadvantage: Very real danger of messing something up, because
344 +
345 +(% style="list-style-type: square;" %)
346 +* schema updates have to be coded in 2 different places in 2 different ways
347 +* the bean definition has to be maintained in 2 places but just 1
348 +
349 +Conclusion: DO NOT DO THIS. This strategy may be ok in very early stages, but at some point it has to be
350 +
351 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Recommendation1:SplitTableDefinitionsfrominitialTableList"/}}Recommendation 1: Split TableDefinitions from initial Table List ===
352 +
353 +If TableDefinitions (pseudo constants for table and column names) go in a dedicated pseudo class it can serve as good overview over the database structure.
354 +
355 +=== {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Recommendation2:FreezeTableDefinition,notafterRC/1.0/GA"/}}Recommendation 2: (% style="font-size: 14.0pt;" %)Freeze Table Definition, not after RC/1.0/GA(%%) ===
356 +
357 +It may be ok to start a new project using a fast changing (% style="font-size: 10.0pt;line-height: 13.0pt;" %)(Initial) Table List.
358 +
359 +(% style="font-size: 10.0pt;line-height: 13.0pt;" %)But, please, freeze it at some point. Once the first test server is setup up, internally or at a friendly customer, the Frozen Initial Table List Strategy is the only valid one!
360 +
237 237  
238 238  
239 239  
Confluence.Code.ConfluencePageClass[0]
Id
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1 -656821
1 +656817
URL
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1 -https://clazzes.atlassian.net/wiki/spaces/JDBC2XML/pages/656821/How To create and update Databases using SchemaManager and SchemaUpdateSnippets
1 +https://clazzes.atlassian.net/wiki/spaces/JDBC2XML/pages/656817/How To create and update Databases using SchemaManager and SchemaUpdateSnippets