Class BTree
- All Implemented Interfaces:
Externalizable
,Serializable
,Comparable
,Formatable
,Storable
,TypedFormat
,Conglomerate
,DataValueDescriptor
,Orderable
- Direct Known Subclasses:
B2I
This generic implementation is expected to be extended by the concreate implementations.
The fields are set when the conglomerate is created and never changed thereafter. When alter table is supported then it will change under the control of a table level lock.
They have package scope because they're read by the scans and controllers.
A table of all conglomerates in the system is maintained by the accessmanager. A cache of conglomerates is maintained in the accessmanager, and references to the read only objects are handed out. A copy of the Conglomerate object is kept in the control row of the root page, so that during logical undo this information can be read without needing to access the possibly corrupt table maintained by the access manager.
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Field Summary
FieldsModifier and TypeFieldDescription(package private) boolean
Whether the index allows duplicates or not.protected boolean[]
protected int[]
The array of collation id's for each column in the template.protected int
Format id of the conglomerate.protected int[]
The array of format id's, one for each column in the template.protected boolean
Tells if there is at least one column in the conglomerate whose collation isn't StringDataValue.COLLATION_TYPE_UCS_BASIC.protected ContainerKey
The id of the container in which this b-tree is stored.(package private) boolean
Whether the parent should maintain links from child pages to their parent.(package private) static int
Maximum rows per page to place on a btree leaf or nonleaf page.protected int
The number of key fields.(package private) int
The number of uniqueness columns.static final String
static final String
Property name for the maximum number of rows to place in a btree page (leaf or branch).static final String
static final String
static final String
static final String
static final long
The page number of the root page is always at the fixed page number: ROOTPAGEID.(package private) boolean
Attribute to indicate the index allows duplicate only in case of keys with no part null.Fields inherited from interface org.apache.derby.iapi.types.DataValueDescriptor
UNKNOWN_LOGICAL_LENGTH
Fields inherited from interface org.apache.derby.iapi.types.Orderable
ORDER_OP_EQUALS, ORDER_OP_GREATEROREQUALS, ORDER_OP_GREATERTHAN, ORDER_OP_LESSOREQUALS, ORDER_OP_LESSTHAN
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
addColumn
(TransactionManager xact_manager, int column_id, Storable template_column, int collation_id) Add a column to the conglomerate.void
create
(Transaction rawtran, int segmentId, long input_containerid, DataValueDescriptor[] template, Properties properties, int conglom_format_id, int tmpFlag) Do the generic part of creating a b-tree conglomerate.(package private) final DataValueDescriptor[]
createBranchTemplate
(Transaction rawtran, DataValueDescriptor page_ptr) Create a branch row template for this conglomerate.final DataValueDescriptor[]
createTemplate
(Transaction rawtran) Create a template for this conglomerate.abstract void
drop
(TransactionManager xact_manager) Drop this btree.protected abstract BTreeLockingPolicy
getBtreeLockingPolicy
(Transaction rawtran, int lock_level, int mode, int isolation_level, ConglomerateController base_cc, OpenBTree open_btree) Create a new btree locking policy from scratch.long
Get the containerid of conglomerate.Return dynamic information about the conglomerate to be dynamically reused in repeated execution of a statement.final ContainerKey
getId()
Get the id of the container of the conglomerate.boolean
isNull()
Return whether the value is null or not.boolean
Is this conglomerate temporary?final boolean
isUnique()
Is this a "unique" index?boolean
Returns if the index type is uniqueWithDuplicateNulls.abstract long
load
(TransactionManager xact_manager, boolean createConglom, RowLocationRetRowSource rowSource) Load a b-tree.abstract ConglomerateController
lockTable
(TransactionManager xact_manager, int open_mode, int lock_level, int isolation_level) Lock the base table.abstract ConglomerateController
open
(TransactionManager xact_manager, Transaction rawtran, boolean hold, int open_mode, int lock_level, LockingPolicy locking_policy, StaticCompiledOpenConglomInfo static_info, DynamicCompiledOpenConglomInfo dynamic_info) Open a b-tree controller.void
Restore the in-memory representation from the stream.void
Restore the in-memory representation to the null value.void
setUniqueWithDuplicateNulls
(boolean uniqueWithDuplicateNulls) Set if the index is unique only for non null keystoString()
Public toString() Method:void
Store the stored representation of the column value in the stream.Methods inherited from class org.apache.derby.impl.store.access.conglomerate.GenericConglomerate
cloneValue, compare, getLength, getNewNull, getObject, getString, getTypeName, hasCollatedColumns, setFrom, setValueFromResultSet
Methods inherited from class org.apache.derby.iapi.types.DataType
checkHostVariable, cloneHolder, coalesce, compare, compare, compare, compareTo, dataTypeConversion, equals, equals, flip, getBoolean, getByte, getBytes, getDate, getDouble, getFloat, getInt, getLong, getShort, getStream, getTime, getTimestamp, getTraceString, greaterOrEquals, greaterThan, hasStream, in, invalidFormat, isNotNull, isNullOp, lessOrEquals, lessThan, normalize, notEquals, outOfRange, readExternalFromArray, recycle, setBigDecimal, setInto, setInto, setObjectForCast, setToNull, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, throwLangSetMismatch, typePrecedence, typeToBigDecimal
Methods inherited from class java.lang.Object
clone, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Methods inherited from interface org.apache.derby.iapi.store.access.conglomerate.Conglomerate
compressConglomerate, defragmentConglomerate, fetchMaxOnBTree, getStaticCompiledConglomInfo, openScan, openStoreCost, purgeConglomerate
Methods inherited from interface org.apache.derby.iapi.types.DataValueDescriptor
checkHostVariable, cloneHolder, coalesce, compare, compare, compare, equals, estimateMemoryUsage, getBoolean, getByte, getBytes, getDate, getDouble, getFloat, getInt, getLong, getShort, getStream, getTime, getTimestamp, getTraceString, greaterOrEquals, greaterThan, hasStream, in, isNotNull, isNullOp, lessOrEquals, lessThan, normalize, notEquals, readExternalFromArray, recycle, setBigDecimal, setInto, setInto, setObjectForCast, setToNull, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, typePrecedence, typeToBigDecimal
Methods inherited from interface org.apache.derby.iapi.services.io.TypedFormat
getTypeFormatId
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Field Details
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ROOTPAGEID
public static final long ROOTPAGEIDThe page number of the root page is always at the fixed page number: ROOTPAGEID. This means that given an open container, during logical undo one can always find the root page and look up the conglomerate information.- See Also:
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PROPERTY_MAX_ROWS_PER_PAGE_PARAMETER
Property name for the maximum number of rows to place in a btree page (leaf or branch). Equal to 'derby.access.btreeMaxRowPerPage'. Used by tests and debugging to exactly control split points, and to make it easier to test tall trees without needing lots of data. -
PROPERTY_ALLOWDUPLICATES
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PROPERTY_NKEYFIELDS
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PROPERTY_NUNIQUECOLUMNS
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PROPERTY_PARENTLINKS
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PROPERTY_UNIQUE_WITH_DUPLICATE_NULLS
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id
The id of the container in which this b-tree is stored. -
nKeyFields
protected int nKeyFieldsThe number of key fields. -
nUniqueColumns
int nUniqueColumnsThe number of uniqueness columns. These are the columns that are considered for the purpose of detecting duplicate keys and rows. -
allowDuplicates
boolean allowDuplicatesWhether the index allows duplicates or not. -
maintainParentLinks
boolean maintainParentLinksWhether the parent should maintain links from child pages to their parent. These links are only used for consistency checking purposes. They improve consistency checking at the cost of run-time efficiency. -
uniqueWithDuplicateNulls
boolean uniqueWithDuplicateNullsAttribute to indicate the index allows duplicate only in case of keys with no part null. This attribute has no effect if unique is true. If unique is false and isUniqueWithDuplicateNulls is set to true the index will allow duplicates of any key with at least one column null, but for non null keys will act like a unique index. -
maxRowsPerPage
static int maxRowsPerPageMaximum rows per page to place on a btree leaf or nonleaf page. Used by testing to finely control split points. Only changed for debugging purposes. RESOLVE (mikem) - this should not be static. Need to design a way in debugging mode to get btree created with a persistent "maxRowsPerPage". This hack makes all btrees get created with the "last" maxRowsPerPage value set. -
conglom_format_id
protected int conglom_format_idFormat id of the conglomerate. -
format_ids
protected int[] format_idsThe array of format id's, one for each column in the template. -
ascDescInfo
protected boolean[] ascDescInfo -
collation_ids
protected int[] collation_idsThe array of collation id's for each column in the template. -
hasCollatedTypes
protected boolean hasCollatedTypesTells if there is at least one column in the conglomerate whose collation isn't StringDataValue.COLLATION_TYPE_UCS_BASIC.
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Constructor Details
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BTree
public BTree()
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Method Details
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getBtreeLockingPolicy
protected abstract BTreeLockingPolicy getBtreeLockingPolicy(Transaction rawtran, int lock_level, int mode, int isolation_level, ConglomerateController base_cc, OpenBTree open_btree) throws StandardException Create a new btree locking policy from scratch.- Throws:
StandardException
- Standard exception policy.
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lockTable
public abstract ConglomerateController lockTable(TransactionManager xact_manager, int open_mode, int lock_level, int isolation_level) throws StandardException Lock the base table.Assumes that segment of the base container is the same as the segment of the btree segment.
RESOLVE - we really want to get the lock without opening the container. raw store will be providing this.
- Parameters:
xact_manager
- Transaction to associate the lock with.- Throws:
StandardException
- Standard exception policy.
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createBranchTemplate
final DataValueDescriptor[] createBranchTemplate(Transaction rawtran, DataValueDescriptor page_ptr) throws StandardException Create a branch row template for this conglomerate.Reads the format id's of each of the columns and manufactures object of the given type for each. It then uses these "empty" objects to create a template row. The object passed in is then added to the last column of the row.
- Returns:
- The new template.
- Throws:
StandardException
- Standard exception policy.
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createTemplate
Create a template for this conglomerate.Reads the format id's of each of the columns and manufactures object of the given type for each. It then uses these "empty" objects to create a template row.
This method is public so that B2IUndo() can call it.
- Returns:
- The new template.
- Throws:
StandardException
- Standard exception policy.
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isUnique
public final boolean isUnique()Is this a "unique" index? -
setUniqueWithDuplicateNulls
public void setUniqueWithDuplicateNulls(boolean uniqueWithDuplicateNulls) Set if the index is unique only for non null keys- Parameters:
uniqueWithDuplicateNulls
- true if the index will be unique only for non null keys
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isUniqueWithDuplicateNulls
public boolean isUniqueWithDuplicateNulls()Returns if the index type is uniqueWithDuplicateNulls.- Returns:
- is index type is uniqueWithDuplicateNulls
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addColumn
public void addColumn(TransactionManager xact_manager, int column_id, Storable template_column, int collation_id) throws StandardException Add a column to the conglomerate.Currently B2I does not support this operation. input template column.
- Parameters:
xact_manager
- Transaction to associate the lock with.column_id
- The column number to add this column at.template_column
- An instance of the column to be added to table.collation_id
- Collation id of the added column.- Throws:
StandardException
- Standard exception policy.
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getId
Get the id of the container of the conglomerate.Will have to change when a conglomerate could have more than one container. The ContainerKey is a combination of the container id and segment id.
- Returns:
- The ContainerKey.
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create
public void create(Transaction rawtran, int segmentId, long input_containerid, DataValueDescriptor[] template, Properties properties, int conglom_format_id, int tmpFlag) throws StandardException Do the generic part of creating a b-tree conglomerate. This method is called from the concrete subclass (which may also read some properties).This method processes all properties which are generic to all BTree's. It creates the container for the btree.
The following properties are generic to a b-tree conglomerate. :
- "allowDuplicates" (boolean). If set to true the table will allow rows which are duplicate in key column's 0 through (nUniqueColumns - 1). Currently only supports "false". This property is optional, defaults to false.
- "nKeyFields" (integer) Columns 0 through (nKeyFields - 1) will be included in key of the conglomerate. This implementation requires that "nKeyFields" must be the same as the number of fields in the conglomerate, including the rowLocationColumn. Other implementations may relax this restriction to allow non-key fields in the index. This property is required.
- "nUniqueColumns" (integer) Columns 0 through "nUniqueColumns" will be used to check for uniqueness. So for a standard SQL non-unique index implementation set "nUniqueColumns" to the same value as "nKeyFields"; and for a unique index set "nUniqueColumns" to "nKeyFields" - 1 (ie. don't include the rowLocationColumn in the uniqueness check). This property is required.
- "maintainParentLinks" (boolean) Whether the b-tree pages maintain the page number of their parent. Only used for consistency checking. It takes a certain amount more effort to maintain these links, but they're really handy for ensuring that the index is consistent. This property is optional, defaults to true.
- Throws:
StandardException
- Thrown by underlying raw store, or thrown by this routine on an invalid containerid.
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drop
Drop this btree. This must be done by a concrete implementation.- Throws:
StandardException
- Standard exception policy.- See Also:
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load
public abstract long load(TransactionManager xact_manager, boolean createConglom, RowLocationRetRowSource rowSource) throws StandardException Load a b-tree. This must be done by a concrete implementation.- Parameters:
xact_manager
- The TransactionController under which this operation takes place.createConglom
- If true, the conglomerate is being created in the same operation as the openAndLoadConglomerate. The enables further optimization as recovery does not require page allocation to be logged.rowSource
- Where the rows come from.- Returns:
- The number of rows loaded.
- Throws:
StandardException
- Standard exception policy.- See Also:
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getContainerid
public long getContainerid()Description copied from interface:Conglomerate
Get the containerid of conglomerate.Will have to change when a conglomerate could have more than one containerid.
- Returns:
- The containerid.
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getDynamicCompiledConglomInfo
Return dynamic information about the conglomerate to be dynamically reused in repeated execution of a statement.The dynamic info is a set of variables to be used in a given ScanController or ConglomerateController. It can only be used in one controller at a time. It is up to the caller to insure the correct thread access to this info. The type of info in this is a scratch template for btree traversal, other scratch variables for qualifier evaluation, ...
- Returns:
- The dynamic information.
- Throws:
StandardException
- Standard exception policy.
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isTemporary
public boolean isTemporary()Is this conglomerate temporary?- Returns:
- whether conglomerate is temporary or not.
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open
public abstract ConglomerateController open(TransactionManager xact_manager, Transaction rawtran, boolean hold, int open_mode, int lock_level, LockingPolicy locking_policy, StaticCompiledOpenConglomInfo static_info, DynamicCompiledOpenConglomInfo dynamic_info) throws StandardException Open a b-tree controller. This must be done by a concrete implementation.- Parameters:
xact_manager
- The access xact to associate all ops on cc with.rawtran
- The raw store xact to associate all ops on cc with.open_mode
- A bit mask of TransactionController.MODE_* bits, indicating info about the open.lock_level
- Either TransactionController.MODE_TABLE or TransactionController.MODE_RECORD, as passed into the openConglomerate() call.locking_policy
- The LockingPolicy to use to open the conglomerate.- Returns:
- The open ConglomerateController.
- Throws:
StandardException
- Standard exception policy.- See Also:
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isNull
public boolean isNull()Return whether the value is null or not. The containerid being zero is what determines nullness; subclasses are not expected to override this method.- Returns:
- true if the value is null and false otherwise.
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restoreToNull
public void restoreToNull()Restore the in-memory representation to the null value. The containerid being zero is what determines nullness; subclasses are not expected to override this method.- See Also:
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readExternal
Restore the in-memory representation from the stream.- Throws:
ClassNotFoundException
- Thrown if the stored representation is serialized and a class named in the stream could not be found.IOException
- thrown by readObject()- See Also:
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writeExternal
Store the stored representation of the column value in the stream. It might be easier to simply store the properties - which would certainly make upgrading easier.- Throws:
IOException
- thrown by writeObject()
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toString
Public toString() Method:
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