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5fbc055b7cc103006957e1ae 2.1 1 = {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Preliminary"/}}Preliminary =
5fbc055b7cc103006957e1ae 1.1 2
christoph_lechleitner@iteg_at 4.1 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.
5fbc055b7cc103006957e1ae 1.1 4
christoph_lechleitner@iteg_at 6.1 5 === {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-SchemaHistoryTable"/}}Schema History Table ===
5fbc055b7cc103006957e1ae 1.1 6
christoph_lechleitner@iteg_at 4.1 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:
8
christoph_lechleitner@iteg_at 6.1 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 )))
5fbc055b7cc103006957e1ae 1.1 58
christoph_lechleitner@iteg_at 6.1 59 === {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-CustomnameforSchemaHistoryTable"/}}Custom name for Schema History Table ===
christoph_lechleitner@iteg_at 4.1 60
christoph_lechleitner@iteg_at 6.1 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
christoph_lechleitner@iteg_at 4.1 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
5fbc055b7cc103006957e1ae 2.1 65 = {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-ProjectConfiguration"/}}Project Configuration =
5fbc055b7cc103006957e1ae 1.1 66
christoph_lechleitner@iteg_at 4.1 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.
5fbc055b7cc103006957e1ae 1.1 68
christoph_lechleitner@iteg_at 4.1 69 Optionally, a base version (default value 0.1.00) and a base description String (default "initial database schema") may be specified.
5fbc055b7cc103006957e1ae 1.1 70
5fbc055b7cc103006957e1ae 2.1 71 Database updates are passed as a Map<String, ISchemaUpdateSnippet> (org.clazzes.jdbc2xml.schema.ISchemaUpdateSnippet) - details see below.
5fbc055b7cc103006957e1ae 1.1 72
5fbc055b7cc103006957e1ae 2.1 73 To perform the operations, call {{code language="none"}}SchemaManager.start(){{/code}}.
74
christoph_lechleitner@iteg_at 4.1 75 === {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-ConfigurationusingSpringorOSGi/Blueprint"/}}Configuration using Spring or OSGi/Blueprint ===
5fbc055b7cc103006957e1ae 2.1 76
77 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):
78
79 {{code language="html/xml"}}
5fbc055b7cc103006957e1ae 1.1 80 <bp:reference id="dialectFactory" interface="org.clazzes.jdbc2xml.schema.IDialectFactory">
81 </bp:reference>
82  
83 <bp:reference id="schemaEngineFactory" interface="org.clazzes.jdbc2xml.schema.ISchemaEngineFactory">
84 </bp:reference>
85  
86 <bp:bean id="sqlDialect" factory-ref="dialectFactory" factory-method="newDialect">
christoph_lechleitner@iteg_at 4.1 87 <bp:argument ref="jdbcUrl"><!-- bean jdbcUrl specified above -->
5fbc055b7cc103006957e1ae 1.1 88 </bp:argument>
89 </bp:bean>
90  
91 <bp:bean id="schemaEngine" factory-ref="schemaEngineFactory" factory-method="newSchemaEngine">
92 <bp:property name="dialect" ref="sqlDialect">
93 </bp:property>
94 </bp:bean>
christoph_lechleitner@iteg_at 7.1 95
5fbc055b7cc103006957e1ae 1.1 96  
christoph_lechleitner@iteg_at 7.1 97 <bp:bean id="initialSchema" class="foo.schema.InitialSchema"></bp:bean>
98  
5fbc055b7cc103006957e1ae 2.1 99 <bp:bean id="databaseSetup" class="org.clazzes.jdbc2xml.schema.SchemaManager" init-method="start">
5fbc055b7cc103006957e1ae 1.1 100 <bp:property name="dataSource" ref="dataSource"></bp:property>
101 <bp:property name="schemaEngine" ref="schemaEngine"></bp:property>
christoph_lechleitner@iteg_at 4.1 102 <!-- optional but recommended: special name for schema history table: -->
103 <bp:property name="versionHistoryTable" value="MYLIB_SCHEMA_HISTORY"/>
104 <!-- optional but recommended: explicit first version -->
5fbc055b7cc103006957e1ae 1.1 105 <bp:property name="baseVersion" value="0.1.00" />
106 <bp:property name="baseTables">
christoph_lechleitner@iteg_at 4.1 107 <!-- List of TableDefinitions here (see below), typical: -->
christoph_lechleitner@iteg_at 7.1 108 <bp:bean factory-ref="initialSchema" factory-method="getSchema" />
5fbc055b7cc103006957e1ae 1.1 109 </bp:property>
christoph_lechleitner@iteg_at 5.1 110 <!-- Add Update-Snippets here, example for updates from 0.1.00 to 0.1.01 and on to 0.2.00
5fbc055b7cc103006957e1ae 1.1 111 <bp:property name="upateSnippets">
christoph_lechleitner@iteg_at 5.1 112 <bp:map>
113 <bp:entry key="0.1.00" value="foo.schema.SchemaUpdate_0_1_01"></bp:entry>
114 <bp:entry key="0.1.01" value="foo.schema.SchemaUpdate_0_2_00"></bp:entry>
115 </bp:map>
5fbc055b7cc103006957e1ae 1.1 116 </bp:property>
christoph_lechleitner@iteg_at 5.1 117 -->
5fbc055b7cc103006957e1ae 1.1 118 </bp:bean>
119 {{/code}}
120
christoph_lechleitner@iteg_at 4.1 121 By default, JDBC2XML provides an implementation of IDialectFactory and ISchemaEngineFactory as an OSGi service or via ServiceRegistry for Spring.
5fbc055b7cc103006957e1ae 2.1 122
123 = {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Settingupaninitialdatabaseschema"/}}Setting up an initial database schema =
124
christoph_lechleitner@iteg_at 7.1 125 === {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-InitalSchema(InitialTableList)"/}}Inital Schema (Initial Table List) ===
126
christoph_lechleitner@iteg_at 4.1 127 To create an initial database schema, SchemaManager needs a list of TableInfo objects.
5fbc055b7cc103006957e1ae 2.1 128
christoph_lechleitner@iteg_at 6.1 129 The recommended strategy is to create an InitialSchema class providing this list through a getter.
christoph_lechleitner@iteg_at 4.1 130
christoph_lechleitner@iteg_at 6.1 131 (% style="font-size: 10.0pt;line-height: 13.0pt;" %)This is an example:
christoph_lechleitner@iteg_at 4.1 132
5fbc055b7cc103006957e1ae 2.1 133 {{code language="java"}}
christoph_lechleitner@iteg_at 7.1 134 package foo.schema;
5fbc055b7cc103006957e1ae 2.1 135
136 import java.sql.Types;
137 import java.util.Arrays;
138 import java.util.List;
139
140 import org.clazzes.jdbc2xml.schema.ColumnInfo;
141 import org.clazzes.jdbc2xml.schema.ForeignKeyInfo;
142 import org.clazzes.jdbc2xml.schema.PrimaryKeyInfo;
143 import org.clazzes.jdbc2xml.schema.TableInfo;
144  
christoph_lechleitner@iteg_at 6.1 145 public class InitialSchema {
5fbc055b7cc103006957e1ae 2.1 146
147 private List<TableInfo> setup;
148
christoph_lechleitner@iteg_at 7.1 149 public InitialSchema() {
5fbc055b7cc103006957e1ae 3.1 150 // Create a table
christoph_lechleitner@iteg_at 7.1 151 TableInfo exampleTable = new TableInfo(TableDefs.TABLENAME_ADDRESSBOOK);
5fbc055b7cc103006957e1ae 2.1 152 exampleTable.setColumns(
153 Arrays.asList(new ColumnInfo[] {
christoph_lechleitner@iteg_at 7.1 154 new ColumnInfo(TableDefs.COL_ADDRESSBOOK_ID, Types.BIGINT, 20, null, false, null,true),
155 new ColumnInfo(TableDefs.COL_ADDRESSBOOK_NAME, Types.VARCHAR, 256, null, false, null),
156 new ColumnInfo(TableDefs.COL_ADDRESSBOOK_ADDRESS_REF, Types.BIGINT, 20, null, true, null),
157 new ColumnInfo(TableDefs.COL_ADDRESSBOOK_BIRTHDAY, Types.DATE, 12, null, false, null)
5fbc055b7cc103006957e1ae 2.1 158 }));
159  
christoph_lechleitner@iteg_at 7.1 160 // Example for creating a primary key
161 exampleTable.setPrimaryKey(
162 new PrimaryKeyInfo("PK_EXAMPLE", COL_ADDRESSBOOK_ID)
163 );
164
5fbc055b7cc103006957e1ae 3.1 165 // Example for creating a foreign key reference
5fbc055b7cc103006957e1ae 2.1 166 exampleTable.setForeignKeys(Arrays.asList(new ForeignKeyInfo[] {
christoph_lechleitner@iteg_at 7.1 167 new ForeignKeyInfo("FK_EXAMPLE_ADDRESS", TableDefs.COL_ADDRESSBOOK_ADDRESS_REF, TableDefs.TABLENAME_ADDRESSES, TableDefs.COL_ADDRESS_ID)
5fbc055b7cc103006957e1ae 2.1 168 }));
169  
5fbc055b7cc103006957e1ae 3.1 170 // ...
5fbc055b7cc103006957e1ae 2.1 171  
172 this.setup = Arrays.asList(
173 exampleTable,
5fbc055b7cc103006957e1ae 3.1 174 // ...
5fbc055b7cc103006957e1ae 2.1 175 );
176
177 }
178  
christoph_lechleitner@iteg_at 6.1 179 public List<TableInfo> getSchema() {
180 return this.schema;
5fbc055b7cc103006957e1ae 2.1 181 }
182
183 }
184 {{/code}}
185
christoph_lechleitner@iteg_at 7.1 186 === {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-TableDefs,acentralplacefortableandcolumnnames"/}}TableDefs, a central place for table and column names ===
christoph_lechleitner@iteg_at 6.1 187
christoph_lechleitner@iteg_at 7.1 188 You may have notice the usage of {{code language="none"}}TableDefs.*{{/code}} members.
christoph_lechleitner@iteg_at 6.1 189
christoph_lechleitner@iteg_at 7.1 190 Table and column names should never be re-typed everywhere as literals, it is highly recommended to use constants.
191
192 Putting these constants in a dedicated class, say {{code language="none"}}TableDef{{/code}}, allows to use this as an easily accessible list of all tables and columns in the database.
193
194 This is an example:
195
196 {{code language="java"}}
197 package foo.schema;
christoph_lechleitner@iteg_at 6.1 198
199 public class TableDefs {
200
201 // It is adviseable to provide the Strings used as names for tables and columns as constants,
202 // so they can be reused savely to construct SQL statements
christoph_lechleitner@iteg_at 7.1 203  
204 // 0.1.00
christoph_lechleitner@iteg_at 6.1 205 public static final String TABLENAME_ADDRESSBOOK = "ADDRESSBOOK";
206 public static final String COL_ADDRESSBOOK_ID = "ID";
207 public static final String COL_ADDRESSBOOK_NAME = "NAME";
208 public static final String COL_ADDRESSBOOK_ADDRESS_REF = "ADDRESS";
209 public static final String COL_ADDRESSBOOK_BIRTHDAY = "BIRTHDAY";
christoph_lechleitner@iteg_at 7.1 210 // 0.1.01
211 public static final String COL_ADDRESSBOOK_GENDER = "GENDER";
212  
christoph_lechleitner@iteg_at 6.1 213 }
214 {{/code}}
215
christoph_lechleitner@iteg_at 7.1 216 === {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Triggeringthecreationoftheinitialschema"/}}Triggering the creation of the initial schema ===
christoph_lechleitner@iteg_at 6.1 217
christoph_lechleitner@iteg_at 7.1 218 (% style="font-size: 10.0pt;line-height: 13.0pt;" %)To trigger the creation of the initial schema when coming across an empty database, (% style="font-size: 10.0pt;line-height: 13.0pt;" %){{code language="none"}}InitialSchema.getSchema(){{/code}} has to be injected into (% style="font-size: 10.0pt;line-height: 13.0pt;" %){{code language="none"}}SchemaManager.setBaseTables(){{/code}} before calling (% style="font-size: 10.0pt;line-height: 13.0pt;" %){{code language="none"}}SchemaManager.start(){{/code}}.
christoph_lechleitner@iteg_at 6.1 219
5fbc055b7cc103006957e1ae 3.1 220 Using Blueprint/Spring, you can do this by inserting the following snippet in the bean definition for SchemaManager:
5fbc055b7cc103006957e1ae 2.1 221
5fbc055b7cc103006957e1ae 3.1 222 {{code language="html/xml"}}
christoph_lechleitner@iteg_at 7.1 223 <bp:bean id="initialSchema" class="foo.schema.InitialSchema"></bp:bean>
224  
5fbc055b7cc103006957e1ae 3.1 225 <bp:property name="baseTables">
christoph_lechleitner@iteg_at 7.1 226 <bp:bean factory-ref="initialSchema" factory-method="getSchema" />
5fbc055b7cc103006957e1ae 3.1 227 </bp:property>
christoph_lechleitner@iteg_at 7.1 228
5fbc055b7cc103006957e1ae 2.1 229 {{/code}}
230
5fbc055b7cc103006957e1ae 3.1 231 = {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-UpdatingadatabaseschemawithISchemaUpdateSnippet"/}}Updating a database schema with ISchemaUpdateSnippet =
5fbc055b7cc103006957e1ae 2.1 232
233 To update the database or it's content with schema updates, you must create a new implementation of ISchemaUpdateSnippet ({{code language="none"}}org.clazzes.jdbc2xml.schema.ISchemaUpdateSnippet{{/code}}) for each consecutive update. SchemaManager takes a {{code language="none"}}Map<String, Class<? extends ISchemaUpdateSnippet>>{{/code}} which contains the update classes keyed by the originating (e.g. previous) version.
234
5fbc055b7cc103006957e1ae 3.1 235 An example for an implementation of a schema update snippet could look like this:
5fbc055b7cc103006957e1ae 2.1 236
5fbc055b7cc103006957e1ae 3.1 237 {{code language="java"}}
christoph_lechleitner@iteg_at 7.1 238 package foo.schema;
5fbc055b7cc103006957e1ae 2.1 239
5fbc055b7cc103006957e1ae 3.1 240 import java.sql.SQLException;
241 import java.sql.Types;
242 import java.util.Arrays;
243 import org.clazzes.jdbc2xml.schema.ColumnInfo;
244 import org.clazzes.jdbc2xml.schema.ISchemaEngine;
245 import org.clazzes.jdbc2xml.schema.ISchemaUpdateSnippet;
246 import org.clazzes.jdbc2xml.schema.PrimaryKeyInfo;
247 import org.clazzes.jdbc2xml.schema.TableInfo;
248
christoph_lechleitner@iteg_at 7.1 249 public class SchemaUpdate_0_1_01 implements ISchemaUpdateSnippet {
5fbc055b7cc103006957e1ae 3.1 250  
251 // This is only accessed through the getter
252 private static final String TARGET_VERSION = "0.1.01";
253  
254 @Override
255 public String getTargetVersion() {
256 return TARGET_VERSION;
257 }
258
259 @Override
260 public String getUpdateComment() {
christoph_lechleitner@iteg_at 7.1 261 return "Adding column "+TableDefs.COL_ADDRESSBOOK_GENDER+" to table "+TableDefs.TABLENAME_ADDRESSBOOK+".";
5fbc055b7cc103006957e1ae 3.1 262 }
263
264 @Override
265 public void performUpdate(ISchemaEngine schemaEngine) throws SQLException {
christoph_lechleitner@iteg_at 7.1 266 TableInfo ti = schemaEngine.fetchTableInfo(TableDefs.TABLENAME_ADDRESSBOOK, null);
267 schemaEngine.addColumn(ti, new ColumnInfo(TableDefs.COL_ADDRESSBOOK_GENDER, Types.VARCHAR, 1, null, true, null));
5fbc055b7cc103006957e1ae 3.1 268 }
269 }
270
271
272 {{/code}}
273
christoph_lechleitner@iteg_at 7.1 274 The return values of {{code language="none"}}ISchemaUpdateSnippet.getTargetVersion(){{/code}} and {{code language="none"}}ISchemaUpdateSnippet.getUpdateComment(){{/code}} are written to the {{code language="none"}}SCHEMA_HISTORY{{/code}} table. The update itself is performed in {{code language="none"}}ISchemaUpdateSnippet.performUpdate(){{/code}}. In the above example, it adds a column called {{code language="none"}}GENDER{{/code}} to the ADDRESSBOOK table created via the InitialSchema class above.
5fbc055b7cc103006957e1ae 3.1 275
276 To add an entire table you would use the {{code language="none"}}ISchemaEngine.createTable(){{/code}} method, like this:
277
278 {{code language="java"}}
279 @Override
280 public void performUpdate(ISchemaEngine schemaEngine) throws SQLException {
281 TableInfo tiGroup = new TableInfo(TB_GROUP);
282 tiGroup.setColumns(Arrays.asList(new ColumnInfo[] {
christoph_lechleitner@iteg_at 7.1 283 new ColumnInfo(TableDefs.COL_ID, Types.VARCHAR, 36, null, false, null),
284 new ColumnInfo(TableDefs.COL_NAME, Types.VARCHAR, 100, null, false, null),
285 new ColumnInfo(TableDefs.COL_DESCRIPTION, Types.VARCHAR, 512, null, true, null)
5fbc055b7cc103006957e1ae 3.1 286 }));
christoph_lechleitner@iteg_at 7.1 287 tiGroup.setPrimaryKey(new PrimaryKeyInfo(PK_GROUP, TableDefs.COL_ID));
288 tiGroup.setIndices(Arrays.asList(new IndexInfo(IDX_GROUP_01, TableDefs.COL_NAME, true, null)));
5fbc055b7cc103006957e1ae 3.1 289
290 schemaEngine.createTable(tiGroup, true);
291 }
292 {{/code}}
293
294 Executing a PreparedStatement also works, using ISchemaEngine.getConnection() to retrieve the database connection:
295
296 {{code language="java"}}
297 @Override
298 public void performUpdate(ISchemaEngine schemaEngine) throws SQLException {
christoph_lechleitner@iteg_at 7.1 299 String sql = "UPDATE "+TableDefs.TB_EXAMPLE_TABLE_NAME+" SET "+TableDefs.COL_EXAMPLE_NAME+"=?";
5fbc055b7cc103006957e1ae 3.1 300
301 PreparedStatement ps = schemaEngine.getConnection().prepareStatement(sql);
302
303 ps.setNull(1, Types.VARCHAR);
304
305 ps.execute();
306 }
307 {{/code}}
308
309 To create the map of updates in Blueprint/Spring and inject them into SchemaManager, use the following xml-Snippet:
310
311 {{code language="html/xml"}}
312 <!-- SchemaManager bean definition starts here ... -->
313 <bp:property name="upateSnippets">
314 <bp:map>
315 <bp:entry key="0.1.00" value="org.clazzes.example.jdbc2xml.updates.SchemaUpdate0_1_01"></bp:entry>
316 <!-- more entries come here: "key" is the schema version to update, "value" the qualified classname of the schema update -->
317 </bp:map>
318 </bp:property>
319 <!-- ... and continues here -->
320 {{/code}}
321
christoph_lechleitner@iteg_at 6.1 322 = {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-SchemaMaintainanceStrategies"/}}Schema Maintainance Strategies =
5fbc055b7cc103006957e1ae 2.1 323
christoph_lechleitner@iteg_at 6.1 324 The JDBC2XML Schema management tools allow for 2 different strategies:
5fbc055b7cc103006957e1ae 2.1 325
christoph_lechleitner@iteg_at 6.1 326 === {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Frozen(Initial)TableList"/}}Frozen (% style="font-size: 14.0pt;" %)(Initial) Table List(%%) ===
327
328 The legacy strategy is:
329
330 (% style="list-style-type: square;" %)
christoph_lechleitner@iteg_at 7.1 331 * At the start of a project, create and use {{code language="none"}}InitalSchema.java{{/code}}
332 * After the first commit, {{code language="none"}}InitalSchema{{/code}} are considered frozen, all changes go into {{code language="none"}}SchemaUpdates{{/code}}, up to one update per source code commit
christoph_lechleitner@iteg_at 6.1 333
334 Advantage: Rock solid.
335
christoph_lechleitner@iteg_at 7.1 336 Disadvantage: No place to look for the complete and exact current scheme, except actual databases. {{code language="none"}}TableDefs.java{{/code}} provide some information, but may become confusing in the long term.
christoph_lechleitner@iteg_at 6.1 337
338 === {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Possiblebutdangerous:Evolving(Initial)TableList"/}}Possible but dangerous: Evolving (Initial) Table List ===
339
christoph_lechleitner@iteg_at 7.1 340 To keep the (Initial) Schema up do date, one might use this strategy:
christoph_lechleitner@iteg_at 6.1 341
342 (% style="list-style-type: square;" %)
christoph_lechleitner@iteg_at 7.1 343 * keep the {{code language="none"}}InitalSchema{{/code}} up to date, so an empty database always gets the current scheme in one shot
344 * {{code language="none"}}SchemaUpdates{{/code}} are only applied to existing databases
christoph_lechleitner@iteg_at 6.1 345
christoph_lechleitner@iteg_at 7.1 346 Advantage: Immediate overview over exact current scheme.
christoph_lechleitner@iteg_at 6.1 347
348 Disadvantage: Very real danger of messing something up, because
349
350 (% style="list-style-type: square;" %)
351 * schema updates have to be coded in 2 different places in 2 different ways
352 * the bean definition has to be maintained in 2 places but just 1
353
christoph_lechleitner@iteg_at 7.1 354 Conclusion: **DO NOT DO THIS**. This strategy may be ok in very early stages, but at some point it has to be
christoph_lechleitner@iteg_at 6.1 355
christoph_lechleitner@iteg_at 7.1 356 === {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-Recommendation:FreezeInitialTableDefinitionnotlaterthanthefirstReleaseCandidate(RC)"/}}(% style="font-size: 14.0pt;" %)Recommendation: Freeze Initial Table Definition not later than the first Release Candidate (RC)(%%) ===
christoph_lechleitner@iteg_at 6.1 357
358 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.
359
360 (% 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!
361
christoph_lechleitner@iteg_at 7.1 362 = {{id name="HowTocreateandupdateDatabasesusingSchemaManagerandSchemaUpdateSnippets-RealworldExample"/}}Real world Example =
5fbc055b7cc103006957e1ae 2.1 363
christoph_lechleitner@iteg_at 7.1 364 This HowTo is currently evolving while an additional developer gets acostumed to the SchemaEngine, for developing [[SDS' org.clazzes.sds.impl.schema package>>url:http://svn.clazzes.org/svn/sds/trunk/sds.impl/src/main/java/org/clazzes/sds/impl/schema||style="font-size: 10.0pt;line-height: 13.0pt;" shape="rect"]](% style="font-size: 10.0pt;line-height: 13.0pt;" %) which is **work in progress**!
5fbc055b7cc103006957e1ae 2.1 365
christoph_lechleitner@iteg_at 7.1 366 (% style="font-size: 10.0pt;line-height: 13.0pt;" %)\\