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96 lines
3.4 KiB
Python
96 lines
3.4 KiB
Python
# Licensed to Elasticsearch B.V. under one or more contributor
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# license agreements. See the NOTICE file distributed with
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# this work for additional information regarding copyright
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# ownership. Elasticsearch B.V. licenses this file to you under
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# the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing,
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# software distributed under the License is distributed on an
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# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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# KIND, either express or implied. See the License for the
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# specific language governing permissions and limitations
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# under the License.
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from typing import TYPE_CHECKING, Optional, TextIO
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if TYPE_CHECKING:
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from .query_compiler import QueryCompiler
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class Index:
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"""
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The index for an eland.DataFrame.
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TODO - This currently has very different behaviour than pandas.Index
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Currently, the index is a field that exists in every document in an Elasticsearch index.
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For slicing and sorting operations it must be a docvalues field. By default _id is used,
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which can't be used for range queries and is inefficient for sorting:
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https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-id-field.html
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(The value of the _id field is also accessible in aggregations or for sorting,
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but doing so is discouraged as it requires to load a lot of data in memory.
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In case sorting or aggregating on the _id field is required, it is advised to duplicate
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the content of the _id field in another field that has doc_values enabled.)
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"""
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ID_INDEX_FIELD = "_id"
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ID_SORT_FIELD = "_doc" # if index field is _id, sort by _doc
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def __init__(
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self, query_compiler: "QueryCompiler", es_index_field: Optional[str] = None
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):
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self._query_compiler = query_compiler
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# _is_source_field is set immediately within
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# index_field.setter
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self._is_source_field = False
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# The type:ignore is due to mypy not being smart enough
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# to recognize the property.setter has a different type
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# than the property.getter.
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self.es_index_field = es_index_field # type: ignore
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@property
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def sort_field(self) -> str:
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if self._index_field == self.ID_INDEX_FIELD:
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return self.ID_SORT_FIELD
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return self._index_field
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@property
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def is_source_field(self) -> bool:
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return self._is_source_field
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@property
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def es_index_field(self) -> str:
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return self._index_field
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@es_index_field.setter
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def es_index_field(self, index_field: Optional[str]) -> None:
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if index_field is None or index_field == Index.ID_INDEX_FIELD:
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self._index_field = Index.ID_INDEX_FIELD
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self._is_source_field = False
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else:
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self._index_field = index_field
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self._is_source_field = True
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def __len__(self) -> int:
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return self._query_compiler._index_count()
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# Make iterable
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def __next__(self) -> None:
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# TODO resolve this hack to make this 'iterable'
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raise StopIteration()
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def __iter__(self) -> "Index":
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return self
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def es_info(self, buf: TextIO) -> None:
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buf.write("Index:\n")
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buf.write(f" es_index_field: {self.es_index_field}\n")
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buf.write(f" is_source_field: {self.is_source_field}\n")
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