Interface ReadableTransaction
- All Known Subinterfaces:
WriteableTransaction
public interface ReadableTransaction
Represents a readable transaction on a storage engine.
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Nested Class Summary
Nested ClassesModifier and TypeInterfaceDescriptionstatic enumOptions applicable toopenCursor(TreeName, ReadOption...). -
Method Summary
Modifier and TypeMethodDescriptiondefault longgetRecordCount(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 ByteStringread(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
nullif 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
0if the tree does not exist.
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