Description

The CTIndex class deal with the index concept. The index is part of the table, and represent one field, or parts of one field, or parts of several fields. One single index may be composed of several segments.

See Also

CTBase, CTField, CTRecord, CTSegment, CTTable

Preconditions

Before any task is developed with a CTIndex object, a CTTable must have been initialized.

CTIndex Operators

• = : Assign a CTIndex object to another

CTIndex.operator=

Syntax

CTIndex operator=( CTIndex aIndex)

Parameters

• aIndex [in] The index object.

Description

Assigns one CTIndex object to another

Return

Returns a CTIndex object

CTIndex Methods

Constructor / Destructor

• CTIndex(): Creates a CTIndex object
• ~CTIndex(): Destroys a CTIndex object and resets all the dependent objects

Key Handling

• GetKeyLength(): Retrieves the key length
• GetKeyType(): Retrieves the key type
• GetEmptyChar(): Retrieves the index empty char
• GetDuplicateFlag(): Retrieves the allow duplicated flag for this index
• GetNullFlag(): Retrieve the null flag
• GetTemporaryFlag(): Retrieves the temporary flag
• SetEmptyChar(): Sets the empty char value
• SetDuplicateFlag(): Sets the allow duplicate flag
• SetNullFlag(): Sets the null flag
• SetTemporaryFlag(): Sets the temporary flag
• SetKeyType(): Set the key type of an index

Segment Handling

• GetSegmentCount(): Retrieves the index segments count
• AddSegment(): Adds a new segment to the index
• InsertSegment(): Inserts a segment to the index
• DelSegment(): Deletes a segment from the index
• GetSegment(): Retrieves an index segment

Index Handling

• GetNumber(): Retrieves the index position in table indexes list.
• GetName(): Retrieves the index name.
• GetUID(): Retrieves the index uid
• GetIdxNo(): Retrieve the index file number
• GetFilename(): Get the index filename
• SetFilename(): Set the index filename
• SetName(): Sets the index name.

CTIndex.CTIndex

Syntax

CTIndex ( )

CTIndex(CTIndex Index)

Parameters

• Index [in] The index object.

Description

This is the constructor for the CTIndex object.

See Also

~CTIndex()

CTIndex.~CTIndex

Syntax

~CTIndex

Parameters

This destructor has no parameters.

Description

This is the destructor for the CTIndex object.

See Also

CTIndex()

CTIndex.AddSegment

Syntax

CTSegment AddSegment( CTField Field, SEG_MODE SegMode)

CTSegment AddSegment(int offset, int length, SEG_MODE SegMode)

Parameters

• Field [in] The segment object to be inserted.
• SegMode [in] The field segment mode. The valid values for the segment mode are shown in "Segment Modes".
• offset [in] The segment offset to be inserted.
• length [in] The segment length to be inserted.

Description

Adds a new segment to the index at the end of the index.

Return

Returns a segment object

See Also

DelSegment(), GetSegmentCount(), InsertSegment()

CTIndex.DelSegment

Syntax

void DelSegment(int SegmentNumber)

Parameters

• SegmentNumber [in] The segment number to be deleted.

Description

Deletes a segment from the index.

Return

None.

See Also

AddSegment(), InsertSegment()

CTIndex.GetDuplicateFlag

Syntax

bool GetDuplicateFlag( )

Parameters

This method has no parameters.

Description

Retrieves the allowed duplicated flag for this index

Return

GetDuplicateFlag() returns true if the index allows duplicated keys, and false otherwise.

See Also

SetDuplicateFlag()

CTIndex.GetEmptyChar

Syntax

int GetEmptyChar( )

Parameters

This method has no parameters.

Description

Retrieves the index empty char.

Return

GetEmptyChar() returns the index empty char. The empty char property is expressed as the decimal equivalent of the ASCII table. See SetEmptyChar() for more information.

See Also

GetNullFlag(), SetEmptyChar()

CTIndex.GetIdxNo

Syntax

int GetIdxNo( )

Parameters

This method has no parameters.

Description

Retrieve the index file number from a index object. If GetIdxno() fails, a CTException is thrown.

Return

GetIdxNo() returns the index file number

CTIndex.GetFileName

Syntax

String GetFilename( )

Parameters

This method has no parameters.

Description

Retrieve the index file name.

Return

GetFileName() returns the index file name

See Also

SetFileName()

CTIndex.GetKeyLength

Syntax

int GetKeyLength( )

Parameters

This method has no parameters.

Description

Retrieves the key length.

Return

GetKeyLength() returns the key length.

See Also

GetKeyType()

CTIndex.GetKeyType

Syntax

KEY_TYPE GetKeyType( )

Parameters

This method has no parameters.

Description

Retrieves the key type.

Return

GetKeyType() returns the key type.

See Also

GetKeyLength(), SetKeyType()

CTIndex.GetName

Syntax

String GetName( )

Parameters

This method has no parameters.

Description

Retrieves the index name.

Return

GetName() returns the index name.

See Also

GetNumber(), GetSegment(), SetName()

CTIndex.GetNullFlag

Syntax

bool GetNullFlag( )

Parameters

This method has no parameters.

Description

Retrieves the null flag.

Return

GetNullFlag() returns true if the null flag is set, and false otherwise

See Also

GetEmptyChar(), SetNullFlag()

CTIndex.GetNumber

Syntax

int GetNumber( )

Parameters

This method has no parameters.

Description

Retrieves the index position in table indexes list.

Return

GetNumber() returns the index position.

See Also

GetName()

CTIndex.GetSegment

Syntax

CTSegment GetSegment(int SegmentNumber)

Parameters

• SegmentNumber [in] The segment number to be retrieved.

Description

Retrieves an index segment.

Return

GetSegment() returns a CTSegment object.

See Also

GetName(), GetNumber(), GetSegmentCount()

CTIndex.GetSegmentCount

Syntax

int GetSegmentCount( )

Parameters

This method has no parameters.

Description

Retrieves the index segments count.

Return

GetSegmentCount() returns the number of segments in the index.

See Also

GetSegment()

CTIndex.GetStatus

Retrieves the status of the index object .

Declaration

ULONG CTIndex.GetStatus() const;

Description

CTIndex.GetStatus() retrieves the status of a index object. The status of the index object is a bit map describing one or more changes that have occurred to the index object.

Return

CTIndex.GetStatus() returns a bitmap of the following:

Example

// if the index has been changed, call alter table

CTIndex hIndex = hTable.GetIndex(0);
 

if (hIndex.GetStatus() != CTDBINDEX_OLD)

if (hTable.Alter(CTDB_ALTER_NORMAL);
 

See Also

CTField.GetStatus(), CTSegment.GetStatus()

CTIndex.GetTemporaryFlag

Syntax

bool GetTemporaryFlag( )

Parameters

This method has no parameters.

Description

Retrieves the temporary flag.

Return

GetTemporaryFlag() returns true if the index is temporary, false otherwise

See Also

SetTemporaryFlag()

CTIndex.GetUID

Syntax

int GetUID( )

Parameters

This method has no parameters.

Description

Retrieves the index UID.

Return

GetUID() returns the index UID.

See Also

GetName()

CTIndex.InsertSegment

Syntax

CTSegment InsertSegment(int BeforeSegment, CTField Field,

SEG_MODE SegMode)

CTSegment InsertSegment(int BeforeSegment, int offset, int length,

SEG_MODE SegMode)

Parameters

• BeforeSegment [in] Insert the new segment before this segment.
• Field [in] The segment object to be inserted.
• SegMode [in] The field segment mode. The valid values for the segment mode are shown in "Segment Modes".
• offset [in] The segment offset to be inserted.
• length [in] The segment length to be inserted.

Description

Inserts a new segment to the index, in a specified position.

Return

Returns a segment object

See Also

AddSegment(), DelSegment(), GetSegmentCount()

CTIndex.MoveSegment

Moves a key segment.

Declaration

void CTIndex.MoveSegment(NINT segmentNumber, NINT newIndex);

Description

CTIndex.MoveSegment() moves a key segment to a location indicated by newIndex. segmentNumber is a relative number for a segment in an index definition and newIndex indicates the relative position were the key segment should be moved to.

Return

void

Example

// move the last segment to first

CTIndex hIndex = hTable.GetIndex(0);

NINT count = hIndex.GetSegmentCount();
 

if (count > 0)

hIndex.MoveSegment((count - 1), 0);
 

See Also

CTTable.MoveSegment(), CTSegment.MoveSegment()

CTIndex.SetDuplicateFlag

Syntax

void SetDuplicateFlag(bool DupFlag)

Parameters

• DupFlag [in] The allow duplicates flag

Description

Sets the allow duplicates flag. If set to true, this index allows duplicated values.

Return

None.

See Also

GetDuplicateFlag()

CTIndex.SetFilename

Syntax

void SetFilename(String Path, String Name)

Parameters

• Path [in] The index path
• Name [in] The index filename

Description

Set the index file path and filename. If filename is NULL the index file name is cleared.

Return

None.

See Also

GetFileName()

CTIndex.SetEmptyChar

Syntax

void SetEmptyChar(int EmptyChar)

Parameters

• EmptyChar [in] The empty char value. The empty char property is expressed as the decimal equivalent of the ASCII table. For instance, an ASCII space is specified as 32, and a NULL byte is specified as 0.

Description

Sets the empty char property.

Return

None.

See Also

GetEmptyChar(), SetNullFlag()

CTIndex.SetKeyType

Syntax

void SetKeyType(KEY_TYPE Type)

Parameters

• keytype [In] - The key type.

Description

SetKeyType() set the key type of an index. The key type can be one of the following values:

• KEY_TYPE.FIXED_INDEX fixed-length key
• KEY_TYPE.LEADING_INDEX leading-character compression
• KEY_TYPE.PADDING_INDEX padding compression
• KEY_TYPE.LEADPAD_INDEX leading/padding compression

Note: Key compression imposes a significant performance impact, especially when deleting records. Use this feature only when absolutely necessary to keep index space requirements to a minimum.

Return

None.

See Also

GetKeyType()

CTIndex.SetName

Syntax

void GetName(String Name )

Parameters

The index name

Description

Sets the index name.

Return

None

See Also

GetName(), GetNumber(), GetSegment()

CTIndex.SetNullFlag

Syntax

void SetNullFlag(bool NullFlag)

Parameters

• NullFlag [in] The new null flag.

Description

Sets the null flag. If set to true, the system checks for NULL or missing key values after the index has been concatenated.

Return

None.

See Also

GetNullFlag(), SetEmptyChar()

CTIndex.SetTemporaryFlag

Syntax

void SetTemporaryFlag(bool TempFlag)

Parameters

• TempFlag [in] The temporary flag.

Description

Sets the temporary flag. If set to true, this index is a temporary index.

Return

None.

See Also

GetTemporaryFlag()