Initial implementation of Cassandra engine

Author: msmygit

.gitignore

@@ -6,3 +6,6 @@ NOTES.md
 
 results/*
 tools/custom/data.json
+
+.venv
+*.DS_Store

engine/clients/cassandra/README.md

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+# Apache Cassandra®
+
+## Setup
+### Pre-requisites
+Adjust the configuration file [`cassandra-single-node.json`](../../../experiments/configurations/cassandra-single-node.json) to your needs. The default configuration is set to use the default Apache Cassandra® settings.
+### Start up the server
+Run the following command to start the server (alternatively, run `docker compose up -d` to run in detached mode):
+```bash
+$ docker compose up
+
+[+] Running 1/1
+ ✔ cassandra Pulled                                                                                                                                                                           1.4s 
+[+] Running 1/1
+ ✔ Container cassandra-benchmark  Recreated                                                                                                                                                   0.1s 
+Attaching to cassandra-benchmark
+cassandra-benchmark  | CompileCommand: dontinline org/apache/cassandra/db/Columns$Serializer.deserializeLargeSubset(Lorg/apache/cassandra/io/util/DataInputPlus;Lorg/apache/cassandra/db/Columns;I)Lorg/apache/cassandra/db/Columns; bool dontinline = true
+...
+cassandra-benchmark  | INFO  [main] 2025-04-04 22:27:38,592 StorageService.java:957 - Cassandra version: 5.0.3
+cassandra-benchmark  | INFO  [main] 2025-04-04 22:27:38,592 StorageService.java:958 - Git SHA: b0226c8ea122c3e5ea8680efb0744d33924fd732
+cassandra-benchmark  | INFO  [main] 2025-04-04 22:27:38,592 StorageService.java:959 - CQL version: 3.4.7
+...
+cassandra-benchmark  | INFO  [main] 2025-04-04 22:28:25,091 StorageService.java:3262 - Node /172.18.0.2:7000 state jump to NORMAL
+```
+> [!TIP]
+> Other helpful commands:
+> - Run `docker exec -it cassandra-benchmark cqlsh` to access the Cassandra shell.
+> - Run `docker compose logs --follow --tail 10` to view & follow the logs of the container running Cassandra.
+
+### Start up the client benchmark
+Run the following command to start the client benchmark using `glove-25-angular` dataset as an example:
+```bash
+% python3 -m run --engines cassandra-single-node --datasets glove-25-angular 
+```
+and you'll see the following output:
+```bash
+Running experiment: cassandra-single-node - glove-25-angular
+Downloading http://ann-benchmarks.com/glove-25-angular.hdf5...
+...
+Experiment stage: Configure
+Experiment stage: Upload
+1183514it [mm:ss, <...>it/s]
+Upload time: <...>
+Index is not ready yet, sleeping for 2 minutes...
+...
+Total import time: <...>
+Experiment stage: Search
+10000it [mm:ss, <...>it/s]
+10000it [mm:ss, <...>it/s]
+Experiment stage: Done
+Results saved to:  /path/to/repository/results
+...
+```
+
+> [!TIP]
+> If you want to see the detailed results, set environment variable `DETAILED_RESULTS=1` before running the benchmark.

engine/clients/cassandra/__init__.py

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+from engine.clients.cassandra.configure import CassandraConfigurator
+from engine.clients.cassandra.search import CassandraSearcher
+from engine.clients.cassandra.upload import CassandraUploader
+
+__all__ = [
+    "CassandraConfigurator",
+    "CassandraSearcher",
+    "CassandraUploader"
+]

engine/clients/cassandra/config.py

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+import os
+
+CASSANDRA_KEYSPACE = os.getenv("CASSANDRA_KEYSPACE", "benchmark")
+CASSANDRA_TABLE = os.getenv("CASSANDRA_TABLE", "vectors")
+ASTRA_API_ENDPOINT = os.getenv("ASTRA_API_ENDPOINT", None)
+ASTRA_API_KEY = os.getenv("ASTRA_API_KEY", None)
+ASTRA_SCB_PATH = os.getenv("ASTRA_SCB_PATH", None)

engine/clients/cassandra/configure.py

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+from cassandra.cluster import Cluster, ExecutionProfile, EXEC_PROFILE_DEFAULT
+from cassandra.policies import DCAwareRoundRobinPolicy, TokenAwarePolicy, ExponentialReconnectionPolicy
+from cassandra import ConsistencyLevel, ProtocolVersion
+
+from benchmark.dataset import Dataset
+from engine.base_client.configure import BaseConfigurator
+from engine.base_client.distances import Distance
+from engine.clients.cassandra.config import CASSANDRA_KEYSPACE, CASSANDRA_TABLE
+
+
+class CassandraConfigurator(BaseConfigurator):
+    SPARSE_VECTOR_SUPPORT = False
+    DISTANCE_MAPPING = {
+        Distance.L2: "euclidean",
+        Distance.COSINE: "cosine",
+        Distance.DOT: "dot_product"
+    }
+
+    def __init__(self, host, collection_params: dict, connection_params: dict):
+        super().__init__(host, collection_params, connection_params)
+        
+        # Set up execution profiles for consistency and performance
+        profile = ExecutionProfile(
+            load_balancing_policy=TokenAwarePolicy(DCAwareRoundRobinPolicy()),
+            consistency_level=ConsistencyLevel.LOCAL_QUORUM,
+            request_timeout=60
+        )
+        
+        # Initialize Cassandra cluster connection
+        self.cluster = Cluster(
+            contact_points=[host],
+            execution_profiles={EXEC_PROFILE_DEFAULT: profile},
+            protocol_version=ProtocolVersion.V4,
+            reconnection_policy=ExponentialReconnectionPolicy(base_delay=1, max_delay=60),
+            **connection_params
+        )
+        self.session = self.cluster.connect()
+
+    def clean(self):
+        """Drop the keyspace if it exists"""
+        self.session.execute(f"DROP KEYSPACE IF EXISTS {CASSANDRA_KEYSPACE}")
+
+    def recreate(self, dataset: Dataset, collection_params):
+        """Create keyspace and table for vector search"""
+        # Create keyspace if not exists
+        self.session.execute(
+            f"""CREATE KEYSPACE IF NOT EXISTS {CASSANDRA_KEYSPACE} 
+            WITH REPLICATION = {{ 'class': 'SimpleStrategy', 'replication_factor': 1 }}"""
+        )
+        
+        # Use the keyspace
+        self.session.execute(f"USE {CASSANDRA_KEYSPACE}")
+        
+        # Get the distance metric
+        distance_metric = self.DISTANCE_MAPPING.get(dataset.config.distance)
+        vector_size = dataset.config.vector_size
+        
+        # Create vector table
+        # Using a simple schema that supports vector similarity search
+        self.session.execute(
+            f"""CREATE TABLE IF NOT EXISTS {CASSANDRA_TABLE} (
+                id int PRIMARY KEY,
+                embedding vector<float, {vector_size}>,
+                metadata map<text, text>
+            )"""
+        )
+        
+        # Create vector index using the appropriate distance metric
+        self.session.execute(
+            f"""CREATE CUSTOM INDEX IF NOT EXISTS vector_index ON {CASSANDRA_TABLE}(embedding) 
+            USING 'StorageAttachedIndex' 
+            WITH OPTIONS = {{ 'similarity_function': '{distance_metric}' }}"""
+        )
+        
+        # Add additional schema fields based on collection_params if needed
+        for field_name, field_type in dataset.config.schema.items():
+            if field_type in ["keyword", "text"]:
+                # For text fields, we would typically add them to metadata
+                pass
+            elif field_type in ["int", "float"]:
+                # For numeric fields that need separate indexing
+                # In a real implementation, we might alter the table to add these columns
+                pass
+        
+        return collection_params
+
+    def execution_params(self, distance, vector_size) -> dict:
+        """Return any execution parameters needed for the dataset"""
+        return {"normalize": distance == Distance.COSINE}
+
+    def delete_client(self):
+        """Close the Cassandra connection"""
+        if hasattr(self, 'session') and self.session:
+            self.session.shutdown()
+        if hasattr(self, 'cluster') and self.cluster:
+            self.cluster.shutdown()

engine/clients/cassandra/parser.py

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+from typing import Any, List, Optional
+
+from engine.base_client.parser import BaseConditionParser, FieldValue
+
+
+class CassandraConditionParser(BaseConditionParser):
+    def build_condition(
+        self, and_subfilters: Optional[List[Any]], or_subfilters: Optional[List[Any]]
+    ) -> Optional[Any]:
+        """
+        Build a CQL condition expression that combines AND and OR subfilters
+        """
+        conditions = []
+        
+        # Add AND conditions
+        if and_subfilters and len(and_subfilters) > 0:
+            and_conds = " AND ".join([f"({cond})" for cond in and_subfilters if cond])
+            if and_conds:
+                conditions.append(f"({and_conds})")
+        
+        # Add OR conditions
+        if or_subfilters and len(or_subfilters) > 0:
+            or_conds = " OR ".join([f"({cond})" for cond in or_subfilters if cond])
+            if or_conds:
+                conditions.append(f"({or_conds})")
+        
+        # Combine all conditions
+        if not conditions:
+            return None
+        
+        return " AND ".join(conditions)
+
+    def build_exact_match_filter(self, field_name: str, value: FieldValue) -> Any:
+        """
+        Build a CQL exact match condition for metadata fields
+        For Cassandra, we format metadata as a map with string values
+        """
+        if isinstance(value, str):
+            return f"metadata['{field_name}'] = '{value}'"
+        else:
+            return f"metadata['{field_name}'] = '{str(value)}'"
+
+    def build_range_filter(
+        self,
+        field_name: str,
+        lt: Optional[FieldValue],
+        gt: Optional[FieldValue],
+        lte: Optional[FieldValue],
+        gte: Optional[FieldValue],
+    ) -> Any:
+        """
+        Build a CQL range filter condition
+        """
+        conditions = []
+        
+        if lt is not None:
+            if isinstance(lt, str):
+                conditions.append(f"metadata['{field_name}'] < '{lt}'")
+            else:
+                conditions.append(f"metadata['{field_name}'] < '{str(lt)}'")
+                
+        if gt is not None:
+            if isinstance(gt, str):
+                conditions.append(f"metadata['{field_name}'] > '{gt}'")
+            else:
+                conditions.append(f"metadata['{field_name}'] > '{str(gt)}'")
+                
+        if lte is not None:
+            if isinstance(lte, str):
+                conditions.append(f"metadata['{field_name}'] <= '{lte}'")
+            else:
+                conditions.append(f"metadata['{field_name}'] <= '{str(lte)}'")
+                
+        if gte is not None:
+            if isinstance(gte, str):
+                conditions.append(f"metadata['{field_name}'] >= '{gte}'")
+            else:
+                conditions.append(f"metadata['{field_name}'] >= '{str(gte)}'")
+        
+        return " AND ".join(conditions)
+
+    def build_geo_filter(
+        self, field_name: str, lat: float, lon: float, radius: float
+    ) -> Any:
+        """
+        Build a CQL geo filter condition
+        Note: Basic Cassandra doesn't have built-in geo filtering.
+        This is a simplified approach that won't actually work without extensions.
+        """
+        # In a real implementation with a geo extension, we'd implement proper geo filtering
+        # For this benchmark, we'll return a placeholder condition that doesn't filter
+        return "1=1"  # Always true condition as a placeholder

engine/clients/cassandra/search.py

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+import multiprocessing as mp
+from typing import List, Tuple
+
+from cassandra.cluster import Cluster, ExecutionProfile, EXEC_PROFILE_DEFAULT
+from cassandra.policies import DCAwareRoundRobinPolicy, TokenAwarePolicy, ExponentialReconnectionPolicy
+from cassandra import ConsistencyLevel, ProtocolVersion
+
+from dataset_reader.base_reader import Query
+from engine.base_client.distances import Distance
+from engine.base_client.search import BaseSearcher
+from engine.clients.cassandra.config import CASSANDRA_KEYSPACE, CASSANDRA_TABLE
+from engine.clients.cassandra.parser import CassandraConditionParser
+
+
+class CassandraSearcher(BaseSearcher):
+    search_params = {}
+    session = None
+    cluster = None
+    parser = CassandraConditionParser()
+
+    @classmethod
+    def init_client(cls, host, distance, connection_params: dict, search_params: dict):
+        # Set up execution profiles for consistency and performance
+        profile = ExecutionProfile(
+            load_balancing_policy=TokenAwarePolicy(DCAwareRoundRobinPolicy()),
+            consistency_level=ConsistencyLevel.LOCAL_ONE,  # Use LOCAL_ONE for faster reads
+            request_timeout=60
+        )
+        
+        # Initialize Cassandra cluster connection
+        cls.cluster = Cluster(
+            contact_points=[host], 
+            execution_profiles={EXEC_PROFILE_DEFAULT: profile},
+            reconnection_policy=ExponentialReconnectionPolicy(base_delay=1, max_delay=60),
+            protocol_version=ProtocolVersion.V4,
+            **connection_params
+        )
+        cls.session = cls.cluster.connect(CASSANDRA_KEYSPACE)
+        cls.search_params = search_params
+        
+        # Update prepared statements with current search parameters
+        cls.update_prepared_statements(distance)
+
+    @classmethod
+    def get_mp_start_method(cls):
+        return "fork" if "fork" in mp.get_all_start_methods() else "spawn"
+
+    @classmethod
+    def update_prepared_statements(cls, distance):
+        """Create prepared statements for vector searches"""
+        # Prepare a vector similarity search query
+        limit = cls.search_params.get("top", 10)
+        
+        if distance == Distance.COSINE:
+            SIMILARITY_FUNC = "similarity_cosine"
+        elif distance == Distance.L2:
+            SIMILARITY_FUNC = "similarity_euclidean"
+        elif distance == Distance.DOT:
+            SIMILARITY_FUNC = "similarity_dot_product"
+        else:
+            raise ValueError(f"Unsupported distance metric: {distance}")
+
+        cls.ann_search_stmt = cls.session.prepare(
+            f"""SELECT id, {SIMILARITY_FUNC}(embedding, ?) as distance 
+            FROM {CASSANDRA_TABLE} 
+            ORDER BY embedding ANN OF ?
+            LIMIT {limit}"""
+        )
+        
+        # Prepare a statement for filtered vector search
+        cls.filtered_search_query_template = (
+            f"""SELECT id, {SIMILARITY_FUNC}(embedding, ?) as distance 
+            FROM {CASSANDRA_TABLE} 
+            WHERE {{conditions}}
+            ORDER BY embedding ANN OF ?
+            LIMIT {limit}"""
+        )
+
+    @classmethod
+    def search_one(cls, query: Query, top: int) -> List[Tuple[int, float]]:
+        """Execute a vector similarity search with optional filters"""
+        # Convert query vector to a format Cassandra can use
+        query_vector = query.vector.tolist() if hasattr(query.vector, 'tolist') else query.vector
+        
+        # Generate filter conditions if metadata conditions exist
+        filter_conditions = cls.parser.parse(query.meta_conditions)
+        
+        try:
+            if filter_conditions:
+                # Use the filtered search query
+                query_with_conditions = cls.filtered_search_query_template.format(conditions=filter_conditions)
+                results = cls.session.execute(
+                    cls.session.prepare(query_with_conditions),
+                    (query_vector, query_vector)
+                )
+            else:
+                # Use the basic ANN search query
+                results = cls.session.execute(
+                    cls.ann_search_stmt,
+                    (query_vector, query_vector)
+                )
+            
+            # Extract and return results
+            return [(row.id, row.distance) for row in results]
+            
+        except Exception as ex:
+            print(f"Error during Cassandra vector search: {ex}")
+            raise ex
+
+    @classmethod
+    def delete_client(cls):
+        """Close the Cassandra connection"""
+        if cls.session:
+            cls.session.shutdown()
+        if cls.cluster:
+            cls.cluster.shutdown()