SchemaComparator (P2J - Progress 4GL to Java Conversion and Runtime)

java.lang.Object
- com.goldencode.p2j.persist.orm.schema.SchemaComparator

public class SchemaComparator
extends java.lang.Object

JDBC schema comparator. Compares current DB schema state with last known state. Last known state may be provided.

Usage:

    SchemaComparator comparator = SchemaComparator.getInstanceExistingState(database);
    ComparisonResult result = comparator.compareWithPrevious();
    if (!result.isSame())
    {
       // Use changes provided by the result
    }

In case it is required to reset the state (server restart, etc.) - this overwrites the last known state file:

    SchemaComparator comparator = SchemaComparator.saveInitialState(database);

Field Summary

Fields
Modifier and Type	Field and Description
`private static java.util.regex.Pattern`	`COMMENT_EXTENT_COLUMN`
`private Database`	`database` Database reference - used for all connections; can't be changed in one instance of the comparator.
`private static java.util.Collection<java.lang.String>`	`EXCLUDED_TABLES` List of lower-case names of tables that should not be used in schema comparison.
`private static java.io.File`	`LAST_KNOWN_STATE_FILE` Path to file into which last known database state is serialized.
`private static DatabaseState`	`lastKnownState` In-memory storage of the last known state.
`private static int`	`MINIMUM_EXTENT_COLUMNS`
`private static java.util.regex.Pattern`	`PATTERN_EXTENT_COLUMN`
`private static java.util.regex.Pattern`	`PATTERN_EXTENT_TABLE`
`private static boolean`	`WRITE_KNOWN_STATE_FILE`
`private static java.lang.String`	`XML_ASCENDING`
`private static java.lang.String`	`XML_COLUMN`
`private static java.lang.String`	`XML_COLUMNS`
`private static java.lang.String`	`XML_COMMENT`
`private static java.lang.String`	`XML_DEFAULT`
`private static java.lang.String`	`XML_INDEX`
`private static java.lang.String`	`XML_NAME`
`private static java.lang.String`	`XML_NULLABLE`
`private static java.lang.String`	`XML_PRECISION`
`private static java.lang.String`	`XML_PRIMARY`
`private static java.lang.String`	`XML_SEQUENCE`
`private static java.lang.String`	`XML_SEQUENCES`
`private static java.lang.String`	`XML_TABLE`
`private static java.lang.String`	`XML_TABLES`
`private static java.lang.String`	`XML_TYPE`
`private static java.lang.String`	`XML_UNIQUE`

Constructor Summary

Constructors
Modifier Constructor and Description

private SchemaComparator(Database database)
Constructor

Constructors
Modifier	Constructor and Description
`private`	`SchemaComparator(Database database)` Constructor

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`ComparisonResult`	`compare(DatabaseState previousState)` Compare current state with given state.
`ComparisonResult`	`compareWithPrevious()` Compare current state with last known state.
`void`	`enrichExtentFields(ComparisonResult result)` EXTENT property of columns are stored in separate tables/columns (normalized/denormalized mode).
`private void`	`getAndCompareColumns(java.sql.Connection conn, DatabaseState previousState, ComparisonResult comparisonResult)` Load information on columns from the provided connection, put the state into result.
`private void`	`getAndCompareIndexes(java.sql.Connection conn, DatabaseState previousState, ComparisonResult comparisonResult)` Load information on indexes from the provided connection, put the state into result.
`private void`	`getAndCompareSequences(java.sql.Connection conn, DatabaseState previousState, ComparisonResult comparisonResult)` Load information on sequences from the provided connection, put the state into result.
`private void`	`getAndCompareTables(java.sql.Connection conn, DatabaseState previousState, ComparisonResult comparisonResult)` Load information on tables from the provided connection, put the state into result.
`ComparisonResult`	`getFreshResult()` Compare current state with an empty database state, effectively reporting everything found in the scan as new.
`static SchemaComparator`	`getInstanceExistingState(Database database)` Get an instance of the Comparator, assuming the current database state file exists (it will be loaded on demand).
`(package private) DatabaseState`	`getLastKnownState()` Load last persisted state.
`void`	`removeTableFromLastKnownState(Table table)` If table validation or DMO generation failed, this method can remove it from result so that it can be loaded next time.
`static SchemaComparator`	`saveInitialState(Database database)` Get an instance of the Comparator, load the current database state for use in comparison.
`(package private) void`	`saveLastKnownState(DatabaseState newState)` Persist the database state.
`private void`	`updateResultByExtentColumn(ComparisonResult result, Table table, int extent, java.lang.String baseName)` Update result to reflect detected EXTENT based on columns (denormalized mode).

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - LAST_KNOWN_STATE_FILE
```
private static final java.io.File LAST_KNOWN_STATE_FILE
```
    Path to file into which last known database state is serialized.
  - WRITE_KNOWN_STATE_FILE
```
private static final boolean WRITE_KNOWN_STATE_FILE
```
    See Also:
    
    Constant Field Values
  - PATTERN_EXTENT_TABLE
```
private static final java.util.regex.Pattern PATTERN_EXTENT_TABLE
```
  - PATTERN_EXTENT_COLUMN
```
private static final java.util.regex.Pattern PATTERN_EXTENT_COLUMN
```
  - COMMENT_EXTENT_COLUMN
```
private static final java.util.regex.Pattern COMMENT_EXTENT_COLUMN
```
  - MINIMUM_EXTENT_COLUMNS
```
private static final int MINIMUM_EXTENT_COLUMNS
```
    See Also:
    
    Constant Field Values
  - XML_TABLES
```
private static final java.lang.String XML_TABLES
```
    See Also:
    
    Constant Field Values
  - XML_TABLE
```
private static final java.lang.String XML_TABLE
```
    See Also:
    
    Constant Field Values
  - XML_COLUMNS
```
private static final java.lang.String XML_COLUMNS
```
    See Also:
    
    Constant Field Values
  - XML_COLUMN
```
private static final java.lang.String XML_COLUMN
```
    See Also:
    
    Constant Field Values
  - XML_INDEX
```
private static final java.lang.String XML_INDEX
```
    See Also:
    
    Constant Field Values
  - XML_ASCENDING
```
private static final java.lang.String XML_ASCENDING
```
    See Also:
    
    Constant Field Values
  - XML_SEQUENCES
```
private static final java.lang.String XML_SEQUENCES
```
    See Also:
    
    Constant Field Values
  - XML_SEQUENCE
```
private static final java.lang.String XML_SEQUENCE
```
    See Also:
    
    Constant Field Values
  - XML_NAME
```
private static final java.lang.String XML_NAME
```
    See Also:
    
    Constant Field Values
  - XML_TYPE
```
private static final java.lang.String XML_TYPE
```
    See Also:
    
    Constant Field Values
  - XML_PRECISION
```
private static final java.lang.String XML_PRECISION
```
    See Also:
    
    Constant Field Values
  - XML_NULLABLE
```
private static final java.lang.String XML_NULLABLE
```
    See Also:
    
    Constant Field Values
  - XML_PRIMARY
```
private static final java.lang.String XML_PRIMARY
```
    See Also:
    
    Constant Field Values
  - XML_UNIQUE
```
private static final java.lang.String XML_UNIQUE
```
    See Also:
    
    Constant Field Values
  - XML_DEFAULT
```
private static final java.lang.String XML_DEFAULT
```
    See Also:
    
    Constant Field Values
  - XML_COMMENT
```
private static final java.lang.String XML_COMMENT
```
    See Also:
    
    Constant Field Values
  - database
```
private final Database database
```
    Database reference - used for all connections; can't be changed in one instance of the comparator.
  - lastKnownState
```
private static DatabaseState lastKnownState
```
    In-memory storage of the last known state. This is to prevent extensive file operations.
  - EXCLUDED_TABLES
```
private static final java.util.Collection<java.lang.String> EXCLUDED_TABLES
```
    List of lower-case names of tables that should not be used in schema comparison. They will be simply ignored when loading tables from the database. NOTE: This configuration may be moved to a file if it becomes too large.
- Constructor Detail
  - SchemaComparator
```
private SchemaComparator(Database database)
```
    Constructor
    
    Parameters:
    
    database - Database reference.
- Method Detail
  - saveInitialState
```
public static SchemaComparator saveInitialState(Database database)
                                         throws PersistenceException
```
    Get an instance of the Comparator, load the current database state for use in comparison. This overwrites the last known state file. Also, it's a blocking operation.
    
    Parameters:
    
    database - Database to which to connect.
    
    Returns:
    
    Comparator instance.
    
    Throws:
    
    PersistenceException
  - getInstanceExistingState
```
public static SchemaComparator getInstanceExistingState(Database database)
```
    Get an instance of the Comparator, assuming the current database state file exists (it will be loaded on demand).
    
    Parameters:
    
    database - Database to which to connect.
    
    Returns:
    
    Comparator instance.
  - getFreshResult
```
public ComparisonResult getFreshResult()
                                throws PersistenceException
```
    Compare current state with an empty database state, effectively reporting everything found in the scan as new.
    
    Returns:
    
    ComparisonResult instance.
    
    Throws:
    
    PersistenceException - if there is an error performing the JDBC scan.
  - compareWithPrevious
```
public ComparisonResult compareWithPrevious()
                                     throws PersistenceException
```
    Compare current state with last known state.
    
    Returns:
    
    ComparisonResult instance.
    
    Throws:
    
    PersistenceException - if there is an error performing the JDBC scan.
  - compare
```
public ComparisonResult compare(DatabaseState previousState)
                         throws PersistenceException
```
    Compare current state with given state.
    
    Parameters:
    
    previousState - Previous known state for comparison.
    
    Returns:
    
    ComparisonResult instance
    
    Throws:
    
    PersistenceException - if there is an error performing the JDBC scan.
  - getLastKnownState
```
DatabaseState getLastKnownState()
                         throws PersistenceException
```
    Load last persisted state. This is to be used on application start.
    
    Returns:
    
    Database state.
    
    Throws:
    
    PersistenceException - if there was an error reading the last known state, other than a file not found error
  - saveLastKnownState
```
void saveLastKnownState(DatabaseState newState)
                 throws PersistenceException
```
    Persist the database state. This is to be used after every successful state comparison.
    
    Parameters:
    
    newState - Database state to persist.
    
    Throws:
    
    PersistenceException
  - getAndCompareTables
```
private void getAndCompareTables(java.sql.Connection conn,
                                 DatabaseState previousState,
                                 ComparisonResult comparisonResult)
                          throws java.sql.SQLException
```
    Load information on tables from the provided connection, put the state into result. If previous state is provided we can compare current state with the previous one and report any differences into result.
    
    Parameters:
    
    conn - Already initiated connection.
    
    previousState - Last known state.
    
    comparisonResult - Instance of result to be filled in.
    
    Throws:
    
    java.sql.SQLException - on unsuccessful calls to DB.
  - getAndCompareColumns
```
private void getAndCompareColumns(java.sql.Connection conn,
                                  DatabaseState previousState,
                                  ComparisonResult comparisonResult)
                           throws java.sql.SQLException
```
    Load information on columns from the provided connection, put the state into result. If previous state is provided, we can compare current state with the previous one and report any differences into result.
    
    Parameters:
    
    conn - Already initiated connection.
    
    previousState - Last known state.
    
    comparisonResult - Instance of result to be filled in.
    
    Throws:
    
    java.sql.SQLException - on unsuccessful calls to DB.
  - getAndCompareIndexes
```
private void getAndCompareIndexes(java.sql.Connection conn,
                                  DatabaseState previousState,
                                  ComparisonResult comparisonResult)
                           throws java.sql.SQLException
```
    Load information on indexes from the provided connection, put the state into result. If previous state is provided, we can compare current state with the previous one and report any differences into result.
    
    Parameters:
    
    conn - Already initiated connection.
    
    previousState - Last known state.
    
    comparisonResult - Instance of result to be filled in.
    
    Throws:
    
    java.sql.SQLException - On unsuccessful calls to DB.
  - getAndCompareSequences
```
private void getAndCompareSequences(java.sql.Connection conn,
                                    DatabaseState previousState,
                                    ComparisonResult comparisonResult)
                             throws java.sql.SQLException
```
    Load information on sequences from the provided connection, put the state into result. If previous state is provided we can compare current state with the previous one and report any differences into result.
    
    Parameters:
    
    conn - Already initiated connection.
    
    previousState - Last known state.
    
    comparisonResult - Instance of result to be filled in.
    
    Throws:
    
    java.sql.SQLException - on unsuccessful calls to DB.
  - removeTableFromLastKnownState
```
public void removeTableFromLastKnownState(Table table)
                                   throws PersistenceException
```
    If table validation or DMO generation failed, this method can remove it from result so that it can be loaded next time.
    
    Parameters:
    
    table - failing table
    
    Throws:
    
    PersistenceException - only thrown if file storage is enabled and writing it fails
  - enrichExtentFields
```
public void enrichExtentFields(ComparisonResult result)
```
    EXTENT property of columns are stored in separate tables/columns (normalized/denormalized mode). This method looks for extent tables and assigns found attributes to the result. Also, extent tables are removed from the result and parent tables are inserted instead. This alters the result (it doesn't fully represent what is available in the database any more), but is required for EXTENT fields to work.
    
    Parameters:
    
    result - Original comparison result
  - updateResultByExtentColumn
```
private void updateResultByExtentColumn(ComparisonResult result,
                                        Table table,
                                        int extent,
                                        java.lang.String baseName)
```
    Update result to reflect detected EXTENT based on columns (denormalized mode).
    
    Parameters:
    
    result - Original comparison result
    
    table - Table containing extent columns
    
    extent - Calculated extent value
    
    baseName - Calculated name of the base column

Class SchemaComparator

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

LAST_KNOWN_STATE_FILE

WRITE_KNOWN_STATE_FILE

PATTERN_EXTENT_TABLE

PATTERN_EXTENT_COLUMN

COMMENT_EXTENT_COLUMN

MINIMUM_EXTENT_COLUMNS

XML_TABLES

XML_TABLE

XML_COLUMNS

XML_COLUMN

XML_INDEX

XML_ASCENDING

XML_SEQUENCES

XML_SEQUENCE

XML_NAME

XML_TYPE

XML_PRECISION

XML_NULLABLE

XML_PRIMARY

XML_UNIQUE

XML_DEFAULT

XML_COMMENT

database

lastKnownState

EXCLUDED_TABLES

Constructor Detail

SchemaComparator

Method Detail

saveInitialState

getInstanceExistingState

getFreshResult

compareWithPrevious

compare

getLastKnownState

saveLastKnownState

getAndCompareTables

getAndCompareColumns

getAndCompareIndexes

getAndCompareSequences

removeTableFromLastKnownState

enrichExtentFields

updateResultByExtentColumn