Interface ReadableTransaction
- All Known Subinterfaces:
WriteableTransaction
public interface ReadableTransaction
Represents a readable transaction on a storage engine.
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Nested Class Summary
Modifier and TypeInterfaceDescriptionstatic enum
Options applicable toopenCursor(TreeName, ReadOption...)
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Method Summary
Modifier and TypeMethodDescriptiondefault long
getRecordCount
(TreeName treeName) Returns the number of key/value pairs in the provided tree.default Cursor<ByteString,
ByteString> openCursor
(TreeName treeName, ReadableTransaction.ReadOption... options) Opens a non-positioned cursor on the tree whose name is provided.default ByteString
read
(TreeName treeName, ByteString key) Reads the record's value associated to the provided key, in the tree whose name is provided.
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Method Details
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read
Reads the record's value associated to the provided key, in the tree whose name is provided.- Parameters:
treeName
- the tree namekey
- the record's key- Returns:
- the record's value, or
null
if none exists or if the tree does not exist.
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openCursor
default Cursor<ByteString,ByteString> openCursor(TreeName treeName, ReadableTransaction.ReadOption... options) Opens a non-positioned cursor on the tree whose name is provided. The cursor will then have to be positioned (e.g: by invokingSequentialCursor.next()
) to bedefined
.- Parameters:
treeName
- the tree nameoptions
- the options to apply to the opened cursor.- Returns:
- a new non-positioned cursor or an empty cursor if the tree does not exist.
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getRecordCount
Returns the number of key/value pairs in the provided tree.- Parameters:
treeName
- the tree name- Returns:
- the number of key/value pairs in the provided tree or
0
if the tree does not exist.
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