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| 1 | +# Copyright (c) QuantCo 2025-2025 |
| 2 | +# SPDX-License-Identifier: BSD-3-Clause |
| 3 | +from __future__ import annotations |
| 4 | + |
| 5 | +from collections.abc import Iterable |
| 6 | +from pathlib import Path |
| 7 | +from typing import Any |
| 8 | + |
| 9 | +import polars as pl |
| 10 | + |
| 11 | +from dataframely._compat import deltalake |
| 12 | + |
| 13 | +from ._base import ( |
| 14 | + SerializedCollection, |
| 15 | + SerializedRules, |
| 16 | + SerializedSchema, |
| 17 | + StorageBackend, |
| 18 | +) |
| 19 | +from ._exc import assert_failure_info_metadata |
| 20 | +from .constants import COLLECTION_METADATA_KEY, RULE_METADATA_KEY, SCHEMA_METADATA_KEY |
| 21 | + |
| 22 | + |
| 23 | +class DeltaStorageBackend(StorageBackend): |
| 24 | + def sink_frame( |
| 25 | + self, lf: pl.LazyFrame, serialized_schema: SerializedSchema, **kwargs: Any |
| 26 | + ) -> None: |
| 27 | + _raise_on_lazy_write() |
| 28 | + |
| 29 | + def write_frame( |
| 30 | + self, df: pl.DataFrame, serialized_schema: SerializedSchema, **kwargs: Any |
| 31 | + ) -> None: |
| 32 | + target = kwargs.pop("target") |
| 33 | + metadata = kwargs.pop("metadata", {}) |
| 34 | + delta_write_options = kwargs.pop("delta_write_options", {}) |
| 35 | + |
| 36 | + # Delta lake does not allow partitioning if there is only one column |
| 37 | + # We dynamically remove this setting here to allow users to still specify it |
| 38 | + # on the collection level without having to worry about each individual member |
| 39 | + if len(df.columns) < 2: |
| 40 | + delta_write_options.pop("partition_by", None) |
| 41 | + |
| 42 | + df.write_delta( |
| 43 | + target, |
| 44 | + delta_write_options=( |
| 45 | + delta_write_options |
| 46 | + | { |
| 47 | + "commit_properties": deltalake.CommitProperties( |
| 48 | + custom_metadata=metadata |
| 49 | + | {SCHEMA_METADATA_KEY: serialized_schema} |
| 50 | + ), |
| 51 | + } |
| 52 | + ), |
| 53 | + **kwargs, |
| 54 | + ) |
| 55 | + |
| 56 | + def scan_frame(self, **kwargs: Any) -> tuple[pl.LazyFrame, SerializedSchema | None]: |
| 57 | + table = _to_delta_table(kwargs.pop("source")) |
| 58 | + serialized_schema = _read_serialized_schema(table) |
| 59 | + df = pl.scan_delta(table, **kwargs) |
| 60 | + return df, serialized_schema |
| 61 | + |
| 62 | + def read_frame(self, **kwargs: Any) -> tuple[pl.DataFrame, SerializedSchema | None]: |
| 63 | + table = _to_delta_table(kwargs.pop("source")) |
| 64 | + serialized_schema = _read_serialized_schema(table) |
| 65 | + df = pl.read_delta(table, **kwargs) |
| 66 | + return df, serialized_schema |
| 67 | + |
| 68 | + # ------------------------------ Collections --------------------------------------- |
| 69 | + def sink_collection( |
| 70 | + self, |
| 71 | + dfs: dict[str, pl.LazyFrame], |
| 72 | + serialized_collection: SerializedCollection, |
| 73 | + serialized_schemas: dict[str, str], |
| 74 | + **kwargs: Any, |
| 75 | + ) -> None: |
| 76 | + _raise_on_lazy_write() |
| 77 | + |
| 78 | + def write_collection( |
| 79 | + self, |
| 80 | + dfs: dict[str, pl.LazyFrame], |
| 81 | + serialized_collection: SerializedCollection, |
| 82 | + serialized_schemas: dict[str, str], |
| 83 | + **kwargs: Any, |
| 84 | + ) -> None: |
| 85 | + uri = Path(kwargs.pop("target")) |
| 86 | + |
| 87 | + # The collection schema is serialized as part of the member parquet metadata |
| 88 | + kwargs["metadata"] = kwargs.get("metadata", {}) | { |
| 89 | + COLLECTION_METADATA_KEY: serialized_collection |
| 90 | + } |
| 91 | + |
| 92 | + for key, lf in dfs.items(): |
| 93 | + self.write_frame( |
| 94 | + lf.collect(), |
| 95 | + serialized_schema=serialized_schemas[key], |
| 96 | + target=uri / key, |
| 97 | + **kwargs, |
| 98 | + ) |
| 99 | + |
| 100 | + def scan_collection( |
| 101 | + self, members: Iterable[str], **kwargs: Any |
| 102 | + ) -> tuple[dict[str, pl.LazyFrame], list[SerializedCollection | None]]: |
| 103 | + uri = Path(kwargs.pop("source")) |
| 104 | + |
| 105 | + data = {} |
| 106 | + collection_types = [] |
| 107 | + for key in members: |
| 108 | + member_uri = uri / key |
| 109 | + if not deltalake.DeltaTable.is_deltatable(str(member_uri)): |
| 110 | + continue |
| 111 | + table = _to_delta_table(member_uri) |
| 112 | + data[key] = pl.scan_delta(table, **kwargs) |
| 113 | + collection_types.append(_read_serialized_collection(table)) |
| 114 | + |
| 115 | + return data, collection_types |
| 116 | + |
| 117 | + def read_collection( |
| 118 | + self, members: Iterable[str], **kwargs: Any |
| 119 | + ) -> tuple[dict[str, pl.LazyFrame], list[SerializedCollection | None]]: |
| 120 | + lazy, collection_types = self.scan_collection(members, **kwargs) |
| 121 | + eager = {name: lf.collect().lazy() for name, lf in lazy.items()} |
| 122 | + return eager, collection_types |
| 123 | + |
| 124 | + # ------------------------------ Failure Info -------------------------------------- |
| 125 | + def sink_failure_info( |
| 126 | + self, |
| 127 | + lf: pl.LazyFrame, |
| 128 | + serialized_rules: SerializedRules, |
| 129 | + serialized_schema: SerializedSchema, |
| 130 | + **kwargs: Any, |
| 131 | + ) -> None: |
| 132 | + _raise_on_lazy_write() |
| 133 | + |
| 134 | + def write_failure_info( |
| 135 | + self, |
| 136 | + df: pl.DataFrame, |
| 137 | + serialized_rules: SerializedRules, |
| 138 | + serialized_schema: SerializedSchema, |
| 139 | + **kwargs: Any, |
| 140 | + ) -> None: |
| 141 | + self.write_frame( |
| 142 | + df, |
| 143 | + serialized_schema, |
| 144 | + metadata={ |
| 145 | + RULE_METADATA_KEY: serialized_rules, |
| 146 | + }, |
| 147 | + **kwargs, |
| 148 | + ) |
| 149 | + |
| 150 | + def scan_failure_info( |
| 151 | + self, **kwargs: Any |
| 152 | + ) -> tuple[pl.LazyFrame, SerializedRules, SerializedSchema]: |
| 153 | + """Lazily read the failure info from the storage backend.""" |
| 154 | + table = _to_delta_table(kwargs.pop("source")) |
| 155 | + |
| 156 | + # Metadata |
| 157 | + serialized_rules = assert_failure_info_metadata(_read_serialized_rules(table)) |
| 158 | + serialized_schema = assert_failure_info_metadata(_read_serialized_schema(table)) |
| 159 | + |
| 160 | + # Data |
| 161 | + lf = pl.scan_delta(table, **kwargs) |
| 162 | + |
| 163 | + return lf, serialized_rules, serialized_schema |
| 164 | + |
| 165 | + |
| 166 | +def _raise_on_lazy_write() -> None: |
| 167 | + raise NotImplementedError("Lazy writes are not currently supported for deltalake.") |
| 168 | + |
| 169 | + |
| 170 | +def _read_serialized_schema(table: deltalake.DeltaTable) -> SerializedSchema | None: |
| 171 | + [last_commit] = table.history(limit=1) |
| 172 | + return last_commit.get(SCHEMA_METADATA_KEY, None) |
| 173 | + |
| 174 | + |
| 175 | +def _read_serialized_collection( |
| 176 | + table: deltalake.DeltaTable, |
| 177 | +) -> SerializedCollection | None: |
| 178 | + [last_commit] = table.history(limit=1) |
| 179 | + return last_commit.get(COLLECTION_METADATA_KEY, None) |
| 180 | + |
| 181 | + |
| 182 | +def _read_serialized_rules( |
| 183 | + table: deltalake.DeltaTable, |
| 184 | +) -> SerializedRules | None: |
| 185 | + [last_commit] = table.history(limit=1) |
| 186 | + return last_commit.get(RULE_METADATA_KEY, None) |
| 187 | + |
| 188 | + |
| 189 | +def _to_delta_table( |
| 190 | + table: Path | str | deltalake.DeltaTable, |
| 191 | +) -> deltalake.DeltaTable: |
| 192 | + from deltalake import DeltaTable |
| 193 | + |
| 194 | + match table: |
| 195 | + case DeltaTable(): |
| 196 | + return table |
| 197 | + case str() | Path(): |
| 198 | + return DeltaTable(table) |
| 199 | + case _: |
| 200 | + raise TypeError(f"Unsupported type {table!r}") |
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