Update javadoc.

Original Pull Request: #3142

Author: christophstrobl

src/main/java/org/springframework/data/redis/connection/ReactiveKeyCommands.java

@@ -242,9 +242,10 @@ default Mono<Long> touch(Collection<ByteBuffer> keys) {
 	Flux<NumericResponse<Collection<ByteBuffer>, Long>> touch(Publisher<Collection<ByteBuffer>> keys);
 
 	/**
-	 * Find all keys matching the given {@literal pattern}.<br />
-	 * It is recommended to use {@link #scan(ScanOptions)} to iterate over the keyspace as {@link #keys(ByteBuffer)} is a
-	 * non-interruptible and expensive Redis operation.
+	 * Retrieve all keys matching the given pattern via {@code KEYS} command.
+	 * <p>
+	 * <strong>IMPORTANT:</strong> This command is non-interruptible and scans the entire keyspace which may cause
+	 * performance issues. Consider {@link #scan(ScanOptions)} for large datasets.
 	 *
 	 * @param pattern must not be {@literal null}.
 	 * @return

src/main/java/org/springframework/data/redis/connection/RedisKeyCommands.java

@@ -119,7 +119,10 @@ default Boolean exists(byte @NonNull [] key) {
 	Long touch(byte @NonNull [] @NonNull... keys);
 
 	/**
-	 * Find all keys matching the given {@code pattern}.
+	 * Retrieve all keys matching the given pattern.
+	 * <p>
+	 * <strong>IMPORTANT:</strong> The {@literal KEYS} command is non-interruptible and scans the entire keyspace which
+	 * may cause performance issues. Consider {@link #scan(ScanOptions)} for large datasets.
 	 *
 	 * @param pattern must not be {@literal null}.
 	 * @return empty {@link Set} if no match found. {@literal null} when used in pipeline / transaction.

src/main/java/org/springframework/data/redis/connection/StringRedisConnection.java

@@ -185,7 +185,10 @@ interface StringTuple extends Tuple {
 	Long touch(@NonNull String @NonNull... keys);
 
 	/**
-	 * Find all keys matching the given {@code pattern}.
+	 * Retrieve all keys matching the given pattern via {@code KEYS} command.
+	 * <p>
+	 * <strong>IMPORTANT:</strong> This command is non-interruptible and scans the entire keyspace which may cause
+	 * performance issues. Consider {@link #scan(ScanOptions)} for large datasets.
 	 *
 	 * @param pattern must not be {@literal null}.
 	 * @return

src/main/java/org/springframework/data/redis/core/ClusterOperations.java

@@ -41,7 +41,10 @@
 public interface ClusterOperations<K, V> {
 
 	/**
-	 * Get all keys located at given node.
+	 * Retrieve all keys located at given node matching the given pattern.
+	 * <p>
+	 * <strong>IMPORTANT:</strong> The {@literal KEYS} command is non-interruptible and scans the entire keyspace which
+	 * may cause performance issues.
 	 *
 	 * @param node must not be {@literal null}.
 	 * @param pattern

src/main/java/org/springframework/data/redis/core/ReactiveRedisOperations.java

@@ -264,9 +264,10 @@ default Mono<Flux<? extends Message<String, V>>> listenToPatternLater(String...
 	Mono<DataType> type(K key);
 
 	/**
-	 * Find all keys matching the given {@code pattern}. <br />
-	 * <strong>IMPORTANT:</strong> It is recommended to use {@link #scan()} to iterate over the keyspace as
-	 * {@link #keys(Object)} is a non-interruptible and expensive Redis operation.
+	 * Retrieve all keys matching the given pattern via {@code KEYS} command.
+	 * <p>
+	 * <strong>IMPORTANT:</strong> This command is non-interruptible and scans the entire keyspace which may cause
+	 * performance issues. Consider {@link #scan(ScanOptions)} for large datasets.
 	 *
 	 * @param pattern must not be {@literal null}.
 	 * @return the {@link Flux} emitting matching keys one by one.

src/main/java/org/springframework/data/redis/core/RedisOperations.java

@@ -264,10 +264,10 @@ public interface RedisOperations<K, V> {
 	DataType type(@NonNull K key);
 
 	/**
-	 * Retrieve keys matching the given pattern via {@code KEYS} command.
+	 * Retrieve all keys matching the given pattern via {@code KEYS} command.
 	 * <p>
-	 * Note: This command scans the entire keyspace and may cause performance issues
-	 * in production environments. Prefer using {@link #scan(ScanOptions)} for large datasets.
+	 * <strong>IMPORTANT:</strong> This command is non-interruptible and scans the entire keyspace which may cause
+	 * performance issues. Consider {@link #scan(ScanOptions)} for large datasets.
 	 *
 	 * @param pattern key pattern
 	 * @return set of matching keys, or {@literal null} when used in pipeline / transaction