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• Client.java

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com.clickhouse.client.api.Client Maven / Gradle / Ivy

package com.clickhouse.client.api;

import com.clickhouse.client.ClickHouseClient;
import com.clickhouse.client.ClickHouseNode;
import com.clickhouse.client.ClickHouseRequest;
import com.clickhouse.client.ClickHouseResponse;
import com.clickhouse.client.api.command.CommandResponse;
import com.clickhouse.client.api.command.CommandSettings;
import com.clickhouse.client.api.data_formats.ClickHouseBinaryFormatReader;
import com.clickhouse.client.api.data_formats.NativeFormatReader;
import com.clickhouse.client.api.data_formats.RowBinaryFormatReader;
import com.clickhouse.client.api.data_formats.RowBinaryWithNamesAndTypesFormatReader;
import com.clickhouse.client.api.data_formats.RowBinaryWithNamesFormatReader;
import com.clickhouse.client.api.data_formats.internal.MapBackedRecord;
import com.clickhouse.client.api.data_formats.internal.ProcessParser;
import com.clickhouse.client.api.enums.Protocol;
import com.clickhouse.client.api.enums.ProxyType;
import com.clickhouse.client.api.insert.DataSerializationException;
import com.clickhouse.client.api.insert.InsertResponse;
import com.clickhouse.client.api.insert.InsertSettings;
import com.clickhouse.client.api.insert.POJOSerializer;
import com.clickhouse.client.api.insert.SerializerNotFoundException;
import com.clickhouse.client.api.internal.ClickHouseLZ4OutputStream;
import com.clickhouse.client.api.internal.ClientStatisticsHolder;
import com.clickhouse.client.api.internal.ClientV1AdaptorHelper;
import com.clickhouse.client.api.internal.HttpAPIClientHelper;
import com.clickhouse.client.api.internal.MapUtils;
import com.clickhouse.client.api.internal.SerializerUtils;
import com.clickhouse.client.api.internal.SettingsConverter;
import com.clickhouse.client.api.internal.TableSchemaParser;
import com.clickhouse.client.api.internal.ValidationUtils;
import com.clickhouse.client.api.metadata.TableSchema;
import com.clickhouse.client.api.metrics.ClientMetrics;
import com.clickhouse.client.api.metrics.OperationMetrics;
import com.clickhouse.client.api.query.GenericRecord;
import com.clickhouse.client.api.query.QueryResponse;
import com.clickhouse.client.api.query.QuerySettings;
import com.clickhouse.client.api.query.Records;
import com.clickhouse.client.config.ClickHouseClientOption;
import com.clickhouse.client.config.ClickHouseDefaults;
import com.clickhouse.client.http.ClickHouseHttpProto;
import com.clickhouse.client.http.config.ClickHouseHttpOption;
import com.clickhouse.data.ClickHouseColumn;
import com.clickhouse.data.ClickHouseFormat;
import com.clickhouse.data.format.BinaryStreamUtils;
import org.apache.hc.client5.http.ConnectTimeoutException;
import org.apache.hc.core5.concurrent.DefaultThreadFactory;
import org.apache.hc.core5.http.ClassicHttpResponse;
import org.apache.hc.core5.http.ConnectionRequestTimeoutException;
import org.apache.hc.core5.http.HttpStatus;
import org.apache.hc.core5.http.NoHttpResponseException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.time.Duration;
import java.time.ZoneId;
import java.time.temporal.ChronoUnit;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.StringJoiner;
import java.util.TimeZone;
import java.util.UUID;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.function.Supplier;

import static java.time.temporal.ChronoUnit.MILLIS;
import static java.time.temporal.ChronoUnit.SECONDS;

/**
 * 
Client is the starting point for all interactions with ClickHouse. 
 *
 * 
{@link Builder} is designed to construct a client object with required configuration:
 *  
{@code
 *
 *  Client client = new Client.Builder()
 *        .addEndpoint(Protocol.HTTP, node.getHost(), node.getPort())
 *        .addUsername("default")
 *        .build();
 *        }
 *  
 *
 *
 * 
When client object is created any operation method can be called on it:
 * 
{@code
 *
 *  if (client.ping()) {
 *      QuerySettings settings = new QuerySettings().setFormat(ClickHouseFormat.RowBinaryWithNamesAndTypes);
 *      Future response = client.query("SELECT * FROM " + table, settings);
 *      QueryResponse queryResponse = response.get();
 *  }
 *  }
 * 
 *
 *
 * 
Client is thread-safe. It uses exclusive set of object to perform an operation.
 *
 */
public class Client implements AutoCloseable {
    private HttpAPIClientHelper httpClientHelper = null;

    private final Set endpoints;
    private final Map configuration;
    private final List serverNodes = new ArrayList<>();
    private final Map, List> serializers; //Order is important to preserve for RowBinary
    private final Map, Map> getterMethods;
    private final Map, Boolean> hasDefaults; // Whether the POJO has defaults
    private static final Logger LOG = LoggerFactory.getLogger(Client.class);
    private final ExecutorService sharedOperationExecutor;

    private final Map globalClientStats = new ConcurrentHashMap<>();

    private boolean useNewImplementation = false;

    private ClickHouseClient oldClient = null;

    private Client(Set endpoints, Map configuration, boolean useNewImplementation,
                   ExecutorService sharedOperationExecutor) {
        this.endpoints = endpoints;
        this.configuration = configuration;
        this.endpoints.forEach(endpoint -> {
            this.serverNodes.add(ClickHouseNode.of(endpoint, this.configuration));
        });
        this.serializers = new HashMap<>();
        this.getterMethods = new HashMap<>();
        this.hasDefaults = new HashMap<>();

        boolean isAsyncEnabled = MapUtils.getFlag(this.configuration, ClickHouseClientOption.ASYNC.getKey());
        if (isAsyncEnabled && sharedOperationExecutor == null) {
            this.sharedOperationExecutor = Executors.newCachedThreadPool(new DefaultThreadFactory("chc-operation"));
        } else {
            this.sharedOperationExecutor = sharedOperationExecutor;
        }
        this.useNewImplementation = useNewImplementation;
        if (useNewImplementation) {
            this.httpClientHelper = new HttpAPIClientHelper(configuration);
            LOG.info("Using new http client implementation");
        } else {
            this.oldClient = ClientV1AdaptorHelper.createClient(configuration);
            LOG.info("Using old http client implementation");
        }
    }

    /**
     * Returns default database name that will be used by operations if not specified.
     *
     * @return String - actual default database name.
     */
    public String getDefaultDatabase() {
        return this.configuration.get("database");
    }


    /**
     * Frees the resources associated with the client.
     * 

     *     
Shuts down the shared operation executor by calling {@code shutdownNow()}
     * 
     */
    @Override
    public void close() {
        try {
            if (sharedOperationExecutor != null && !sharedOperationExecutor.isShutdown()) {
                this.sharedOperationExecutor.shutdownNow();
            }
        } catch (Exception e) {
            LOG.error("Failed to close shared operation executor", e);
        }

        if (oldClient != null) {
            oldClient.close();
        }
    }

    public static class Builder {
        private Set endpoints;

        // Read-only configuration
        private Map configuration;
        private boolean useNewImplementation = false;

        private ExecutorService sharedOperationExecutor = null;

        public Builder() {
            this.endpoints = new HashSet<>();
            this.configuration = new HashMap();
            // TODO: set defaults configuration values
            this.setConnectTimeout(30, SECONDS)
                    .setSocketTimeout(2, SECONDS)
                    .setSocketRcvbuf(804800)
                    .setSocketSndbuf(804800)
                    .compressServerResponse(true)
                    .compressClientRequest(false);
        }

        /**
         * Server address to which client may connect. If there are multiple endpoints then client will
         * connect to one of them.
         * Acceptable formats are:
         * 

         *     
{@code http://localhost:8123}
         *     
{@code https://localhost:8443}
         * 
         *
         * @param endpoint - URL formatted string with protocol, host and port.
         */
        public Builder addEndpoint(String endpoint) {
            try {
                URL endpointURL = new java.net.URL(endpoint);

                if (endpointURL.getProtocol().equalsIgnoreCase("https")) {
                    addEndpoint(Protocol.HTTP, endpointURL.getHost(), endpointURL.getPort(), true);
                } else if (endpointURL.getProtocol().equalsIgnoreCase("http")) {
                    addEndpoint(Protocol.HTTP, endpointURL.getHost(), endpointURL.getPort(), false);
                } else {
                    throw new IllegalArgumentException("Only HTTP and HTTPS protocols are supported");
                }
            } catch (java.net.MalformedURLException e) {
                throw new IllegalArgumentException("Endpoint should be a valid URL string", e);
            }
            return this;
        }

        /**
         * Server address to which client may connect. If there are multiple endpoints then client will
         * connect to one of them.
         *
         * @param protocol - Endpoint protocol
         * @param host - Endpoint host
         * @param port - Endpoint port
         */
        public Builder addEndpoint(Protocol protocol, String host, int port, boolean secure) {
            ValidationUtils.checkNonBlank(host, "host");
            ValidationUtils.checkNotNull(protocol, "protocol");
            ValidationUtils.checkRange(port, 1, ValidationUtils.TCP_PORT_NUMBER_MAX, "port");
            if (secure) {
                // For some reason com.clickhouse.client.http.ApacheHttpConnectionImpl.newConnection checks only client config
                // for SSL, so we need to set it here. But it actually should be set for each node separately.
                this.configuration.put(ClickHouseClientOption.SSL.getKey(), "true");
            }
            String endpoint = String.format("%s%s://%s:%d", protocol.toString().toLowerCase(), secure ? "s": "", host, port);
            this.endpoints.add(endpoint);
            return this;
        }


        /**
         * Sets a configuration option. This method can be used to set any configuration option.
         * There is no specific validation is done on the key or value.
         *
         * @param key - configuration option name
         * @param value - configuration option value
         */
        public Builder setOption(String key, String value) {
            this.configuration.put(key, value);
            return this;
        }

        /**
         * Username for authentication with server. Required for all operations.
         * Same username will be used for all endpoints.
         *
         * @param username - a valid username
         */
        public Builder setUsername(String username) {
            this.configuration.put("user", username);
            return this;
        }

        /**
         * Password for authentication with server. Required for all operations.
         * Same password will be used for all endpoints.
         *
         * @param password - plain text password
         */
        public Builder setPassword(String password) {
            this.configuration.put("password", password);
            return this;
        }

        /**
         * Access token for authentication with server. Required for all operations.
         * Same access token will be used for all endpoints.
         *
         * @param accessToken - plain text access token
         */
        public Builder setAccessToken(String accessToken) {
            this.configuration.put("access_token", accessToken);
            return this;
        }

        /**
         * Configures client to use build-in connection pool
         * @param enable - if connection pool should be enabled
         * @return
         */
        public Builder enableConnectionPool(boolean enable) {
            this.configuration.put("connection_pool_enabled", String.valueOf(enable));
            return this;
        }

        /**
         * Default connection timeout in milliseconds. Timeout is applied to establish a connection.
         *
         * @param timeout - connection timeout in milliseconds
         */
        public Builder setConnectTimeout(long timeout) {
            this.configuration.put("connect_timeout", String.valueOf(timeout));
            return this;
        }

        /**
         * Default connection timeout in milliseconds. Timeout is applied to establish a connection.
         *
         * @param timeout - connection timeout value
         * @param unit - time unit
         */
        public Builder setConnectTimeout(long timeout, ChronoUnit unit) {
            return this.setConnectTimeout(Duration.of(timeout, unit).toMillis());
        }

        /**
         * Set timeout for waiting a free connection from a pool when all connections are leased.
         * This configuration is important when need to fail fast in high concurrent scenarios.
         * Default is 10 s.
         * @param timeout - connection timeout in milliseconds
         * @param unit - time unit
         */
        public Builder setConnectionRequestTimeout(long timeout, ChronoUnit unit) {
            this.configuration.put("connection_request_timeout", String.valueOf(Duration.of(timeout, unit).toMillis()));
            return this;
        }

        /**
         * Sets the maximum number of connections that can be opened at the same time to a single server. Limit is not
         * a hard stop. It is done to prevent threads stuck inside a connection pool waiting for a connection.
         * Default is 10. It is recommended to set a higher value for a high concurrent applications. It will let
         * more threads to get a connection and execute a query.
         *
         * @param maxConnections - maximum number of connections
         */
        public Builder setMaxConnections(int maxConnections) {
            this.configuration.put(ClickHouseHttpOption.MAX_OPEN_CONNECTIONS.getKey(), String.valueOf(maxConnections));
            return this;
        }

        /**
         * Sets how long any connection would be considered as active and able for a lease.
         * After this time connection will be marked for sweep and will not be returned from a pool.
         * Has more effect than keep-alive timeout.
         * @param timeout - time in unit
         * @param unit - time unit
         * @return
         */
        public Builder setConnectionTTL(long timeout, ChronoUnit unit) {
            this.configuration.put(ClickHouseClientOption.CONNECTION_TTL.getKey(), String.valueOf(Duration.of(timeout, unit).toMillis()));
            return this;
        }

        /**
         * Sets keep alive timeout for a connection to override server value. If set to -1 then server value will be used.
         * Default is -1.
         * Doesn't override connection TTL value.
         * {@see Client#setConnectionTTL}
         * @param timeout - time in unit
         * @param unit - time unit
         * @return
         */
        public Builder setKeepAliveTimeout(long timeout, ChronoUnit unit) {
            this.configuration.put(ClickHouseHttpOption.KEEP_ALIVE_TIMEOUT.getKey(), String.valueOf(Duration.of(timeout, unit).toMillis()));
            return this;
        }

        /**
         * Sets strategy of how connections are reuse.
         * Default is {@link ConnectionReuseStrategy#FIFO} to evenly distribute load between them.
         *
         * @param strategy - strategy for connection reuse
         * @return
         */
        public Builder setConnectionReuseStrategy(ConnectionReuseStrategy strategy) {
            this.configuration.put("connection_reuse_strategy", strategy.name());
            return this;
        }

        // SOCKET SETTINGS

        /**
         * Default socket timeout in milliseconds. Timeout is applied to read and write operations.
         *
         * @param timeout - socket timeout in milliseconds
         */
        public Builder setSocketTimeout(long timeout) {
            this.configuration.put("socket_timeout", String.valueOf(timeout));
            return this;
        }

        /**
         * Default socket timeout in milliseconds. Timeout is applied to read and write operations.
         *
         * @param timeout - socket timeout value
         * @param unit - time unit
         */
        public Builder setSocketTimeout(long timeout, ChronoUnit unit) {
            return this.setSocketTimeout(Duration.of(timeout, unit).toMillis());
        }

        /**
         * Default socket receive buffer size in bytes.
         *
         * @param size - socket receive buffer size in bytes
         */
        public Builder setSocketRcvbuf(long size) {
            this.configuration.put("socket_rcvbuf", String.valueOf(size));
            return this;
        }

        /**
         * Default socket send buffer size in bytes.
         *
         * @param size - socket send buffer size in bytes
         */
        public Builder setSocketSndbuf(long size) {
            this.configuration.put("socket_sndbuf", String.valueOf(size));
            return this;
        }

        /**
         * Default socket reuse address option.
         *
         * @param value - socket reuse address option
         */
        public Builder setSocketReuseAddress(boolean value) {
            this.configuration.put("socket_reuseaddr", String.valueOf(value));
            return this;
        }

        /**
         * Default socket keep alive option.If set to true socket will be kept alive
         * until terminated by one of the parties.
         *
         * @param value - socket keep alive option
         */
        public Builder setSocketKeepAlive(boolean value) {
            this.configuration.put("socket_keepalive", String.valueOf(value));
            return this;
        }

        /**
         * Default socket tcp_no_delay option. If set to true, disables Nagle's algorithm.
         *
         * @param value - socket tcp no delay option
         */
        public Builder setSocketTcpNodelay(boolean value) {
            this.configuration.put("socket_tcp_nodelay", String.valueOf(value));
            return this;
        }

        /**
         * Default socket linger option. If set to true, socket will linger for the specified time.
         *
         * @param secondsToWait - socket linger time in seconds
         */
        public Builder setSocketLinger(int secondsToWait) {
            this.configuration.put("socket_linger", String.valueOf(secondsToWait));
            return this;
        }

        /**
         * Server response compression. If set to true server will compress the response.
         * Has most effect for read operations.
         *
         * @param enabled - indicates if server response compression is enabled
         */
        public Builder compressServerResponse(boolean enabled) {
            this.configuration.put(ClickHouseClientOption.COMPRESS.getKey(), String.valueOf(enabled));
            return this;
        }

        /**
         * Client request compression. If set to true client will compress the request.
         * Has most effect for write operations.
         *
         * @param enabled - indicates if client request compression is enabled
         */
        public Builder compressClientRequest(boolean enabled) {
            this.configuration.put(ClickHouseClientOption.DECOMPRESS.getKey(), String.valueOf(enabled));
            return this;
        }

        /**
         * Configures the client to use HTTP compression. In this case compression is controlled by
         * http headers. Client compression will set {@code Content-Encoding: lz4} header and server
         * compression will set {@code Accept-Encoding: lz4} header.
         *
         * @param enabled - indicates if http compression is enabled
         * @return
         */
        public Builder useHttpCompression(boolean enabled) {
            this.configuration.put("client.use_http_compression", String.valueOf(enabled));
            return this;
        }

        /**
         * Sets buffer size for uncompressed data in LZ4 compression.
         * For outgoing data it is the size of a buffer that will be compressed.
         * For incoming data it is the size of a buffer that will be decompressed.
         *
         * @param size - size of the buffer in bytes
         * @return
         */
        public Builder setLZ4UncompressedBufferSize(int size) {
            this.configuration.put("compression.lz4.uncompressed_buffer_size", String.valueOf(size));
            return this;
        }

        /**
         * Sets the default database name that will be used by operations if not specified.
         * @param database - actual default database name.
         */
        public Builder setDefaultDatabase(String database) {
            this.configuration.put("database", database);
            return this;
        }

        public Builder addProxy(ProxyType type, String host, int port) {
            ValidationUtils.checkNotNull(type, "type");
            ValidationUtils.checkNonBlank(host, "host");
            ValidationUtils.checkRange(port, 1, ValidationUtils.TCP_PORT_NUMBER_MAX, "port");

            this.configuration.put(ClickHouseClientOption.PROXY_TYPE.getKey(), type.name());
            this.configuration.put(ClickHouseClientOption.PROXY_HOST.getKey(), host);
            this.configuration.put(ClickHouseClientOption.PROXY_PORT.getKey(), String.valueOf(port));
            return this;
        }

        public Builder setProxyCredentials(String user, String pass) {
            this.configuration.put("proxy_user", user);
            this.configuration.put("proxy_password", pass);
            return this;
        }

        /**
         * Sets the maximum time for operation to complete. By default, it is set to 3 hours.
         * @param timeout
         * @param timeUnit
         * @return
         */
        public Builder setExecutionTimeout(long timeout, ChronoUnit timeUnit) {
            this.configuration.put(ClickHouseClientOption.MAX_EXECUTION_TIME.getKey(), String.valueOf(Duration.of(timeout, timeUnit).toMillis()));
            return this;
        }

        /**
         * Switches to new implementation of the client.
         * @deprecated - do not use - it is only for development
         */
        public Builder useNewImplementation(boolean useNewImplementation) {
            this.useNewImplementation = useNewImplementation;
            return this;
        }

        public Builder setHttpCookiesEnabled(boolean enabled) {
            //TODO: extract to settings string constants
            this.configuration.put("client.http.cookies_enabled", String.valueOf(enabled));
            return this;
        }


        /**
         * Defines path to the trust store file. It cannot be combined with
         * certificates. Either trust store or certificates should be used.
         *
         * {@see setSSLTrustStorePassword} and {@see setSSLTrustStoreType}
         * @param path
         * @return
         */
        public Builder setSSLTrustStore(String path) {
            this.configuration.put(ClickHouseClientOption.TRUST_STORE.getKey(), path);
            return this;
        }

        /**
         * Password for the SSL Trust Store.
         *
         * @param password
         * @return
         */
        public Builder setSSLTrustStorePassword(String password) {
            this.configuration.put(ClickHouseClientOption.KEY_STORE_PASSWORD.getKey(), password);
            return this;
        }

        /**
         * Type of the SSL Trust Store. Usually JKS
         *
         * @param type
         * @return
         */
        public Builder setSSLTrustStoreType(String type) {
            this.configuration.put(ClickHouseClientOption.KEY_STORE_TYPE.getKey(), type);
            return this;
        }

        /**
         * Defines path to the key store file. It cannot be combined with
         * certificates. Either key store or certificates should be used.
         *
         * {@see setSSLKeyStorePassword} and {@see setSSLKeyStoreType}
         * @param path
         * @return
         */
        public Builder setRootCertificate(String path) {
            this.configuration.put(ClickHouseClientOption.SSL_ROOT_CERTIFICATE.getKey(), path);
            return this;
        }

        /**
         * Client certificate for mTLS.
         * @param path
         * @return
         */
        public Builder setClientCertificate(String path) {
            this.configuration.put(ClickHouseClientOption.SSL_CERTIFICATE.getKey(), path);
            return this;
        }

        /**
         * Client key for mTLS.
         * @param path
         * @return
         */
        public Builder setClientKey(String path) {
            this.configuration.put(ClickHouseClientOption.SSL_KEY.getKey(), path);
            return this;
        }

        /**
         * Configure client to use server timezone for date/datetime columns. Default is true.
         * If this options is selected then server timezone should be set as well.
         *
         * @param useServerTimeZone - if to use server timezone
         * @return
         */
        public Builder useServerTimeZone(boolean useServerTimeZone) {
            this.configuration.put(ClickHouseClientOption.USE_SERVER_TIME_ZONE.getKey(), String.valueOf(useServerTimeZone));
            return this;
        }

        /**
         * Configure client to use specified timezone. If set using server TimeZone should be
         * set to false
         *
         * @param timeZone
         * @return
         */
        public Builder useTimeZone(String timeZone) {
            this.configuration.put(ClickHouseClientOption.USE_TIME_ZONE.getKey(), timeZone);
            return this;
        }

        /**
         * Specify server timezone to use. If not set then UTC will be used.
         *
         * @param timeZone - server timezone
         * @return
         */
        public Builder setServerTimeZone(String timeZone) {
            this.configuration.put(ClickHouseClientOption.SERVER_TIME_ZONE.getKey(), timeZone);
            return this;
        }

        /**
         * Configures client to execute requests in a separate thread. By default, operations (query, insert)
         * are executed in the same thread as the caller.
         * It is possible to set a shared executor for all operations. See {@link #setSharedOperationExecutor(ExecutorService)}
         *
         * Note: Async operations a using executor what expects having a queue of tasks for a pool of executors.
         * The queue size limit is small it may quickly become a problem for scheduling new tasks.
         *
         * @param async - if to use async requests
         * @return
         */
        public Builder useAsyncRequests(boolean async) {
            this.configuration.put(ClickHouseClientOption.ASYNC.getKey(), String.valueOf(async));
            return this;
        }

        /**
         * Sets an executor for running operations. If async operations are enabled and no executor is specified
         * client will create a default executor.
         *
         * @param executorService - executor service for async operations
         * @return
         */
        public Builder setSharedOperationExecutor(ExecutorService executorService) {
            this.sharedOperationExecutor = executorService;
            return this;
        }

        /**
         * Set size of a buffers that are used to read/write data from the server. It is mainly used to copy data from
         * a socket to application memory and visa-versa. Setting is applied for both read and write operations.
         * Default is 8192 bytes.
         *
         * @param size - size in bytes
         * @return
         */
        public Builder setClientNetworkBufferSize(int size) {
            this.configuration.put("client_network_buffer_size", String.valueOf(size));
            return this;
        }


        /**
         * Sets list of causes that should be retried on.
         * Default {@code [NoHttpResponse, ConnectTimeout, ConnectionRequestTimeout]}
         * Use {@link ClientFaultCause#None} to disable retries.
         *
         * @param causes - list of causes
         * @return
         */
        public Builder retryOnFailures(ClientFaultCause ...causes) {
            StringJoiner joiner = new StringJoiner(VALUES_LIST_DELIMITER);
            for (ClientFaultCause cause : causes) {
                joiner.add(cause.name());
            }
            this.configuration.put("client_retry_on_failures", joiner.toString());
            return this;
        }

        public Builder setMaxRetries(int maxRetries) {
            this.configuration.put(ClickHouseClientOption.RETRY.getKey(), String.valueOf(maxRetries));
            return this;
        }

        public Client build() {
            setDefaults();

            // check if endpoint are empty. so can not initiate client
            if (this.endpoints.isEmpty()) {
                throw new IllegalArgumentException("At least one endpoint is required");
            }
            // check if username and password are empty. so can not initiate client?
            if (!this.configuration.containsKey("access_token") && (!this.configuration.containsKey("user") || !this.configuration.containsKey("password"))) {
                throw new IllegalArgumentException("Username and password are required");
            }

            if (this.configuration.containsKey(ClickHouseClientOption.TRUST_STORE) &&
                this.configuration.containsKey(ClickHouseClientOption.SSL_CERTIFICATE)) {
                throw new IllegalArgumentException("Trust store and certificates cannot be used together");
            }

            // Check timezone settings
            String useTimeZoneValue = this.configuration.get(ClickHouseClientOption.USE_TIME_ZONE.getKey());
            String serverTimeZoneValue = this.configuration.get(ClickHouseClientOption.SERVER_TIME_ZONE.getKey());
            boolean useServerTimeZone = MapUtils.getFlag(this.configuration, ClickHouseClientOption.USE_SERVER_TIME_ZONE.getKey());
            if (useTimeZoneValue != null) {
                if (useServerTimeZone) {
                    throw new IllegalArgumentException("USE_TIME_ZONE option cannot be used when using server timezone");
                }

                try {
                    LOG.info("Using timezone: {} instead of server one", ZoneId.of(useTimeZoneValue));
                } catch (Exception e) {
                    throw new IllegalArgumentException("Invalid timezone value: " + useTimeZoneValue);
                }
            } else if (useServerTimeZone) {
                if (serverTimeZoneValue == null) {
                    serverTimeZoneValue = "UTC";
                }

                try {
                    LOG.info("Using server timezone: {}", ZoneId.of(serverTimeZoneValue));
                } catch (Exception e) {
                    throw new IllegalArgumentException("Invalid server timezone value: " + serverTimeZoneValue);
                }
            } else {
                throw new IllegalArgumentException("Nor server timezone nor specific timezone is set");
            }

            return new Client(this.endpoints, this.configuration, this.useNewImplementation, this.sharedOperationExecutor);
        }

        private static final int DEFAULT_NETWORK_BUFFER_SIZE = 300_000;

        private void setDefaults() {

            // set default database name if not specified
            if (!configuration.containsKey("database")) {
                setDefaultDatabase((String) ClickHouseDefaults.DATABASE.getDefaultValue());
            }

            if (!configuration.containsKey(ClickHouseClientOption.MAX_EXECUTION_TIME.getKey())) {
                setExecutionTimeout(0, MILLIS);
            }

            if (!configuration.containsKey(ClickHouseClientOption.MAX_THREADS_PER_CLIENT.getKey())) {
                configuration.put(ClickHouseClientOption.MAX_THREADS_PER_CLIENT.getKey(),
                        String.valueOf(ClickHouseClientOption.MAX_THREADS_PER_CLIENT.getDefaultValue()));
            }

            if (!configuration.containsKey("compression.lz4.uncompressed_buffer_size")) {
                setLZ4UncompressedBufferSize(ClickHouseLZ4OutputStream.UNCOMPRESSED_BUFF_SIZE);
            }

            if (!configuration.containsKey(ClickHouseClientOption.USE_SERVER_TIME_ZONE.getKey())) {
                useServerTimeZone(true);
            }

            if (!configuration.containsKey(ClickHouseClientOption.SERVER_TIME_ZONE.getKey())) {
                setServerTimeZone("UTC");
            }

            if (!configuration.containsKey(ClickHouseClientOption.ASYNC.getKey())) {
                useAsyncRequests(false);
            }

            if (!configuration.containsKey(ClickHouseHttpOption.MAX_OPEN_CONNECTIONS.getKey())) {
                setMaxConnections(10);
            }

            if (!configuration.containsKey("connection_request_timeout")) {
                setConnectionRequestTimeout(10, SECONDS);
            }

            if (!configuration.containsKey("connection_reuse_strategy")) {
                setConnectionReuseStrategy(ConnectionReuseStrategy.FIFO);
            }

            if (!configuration.containsKey("connection_pool_enabled")) {
                enableConnectionPool(true);
            }

            if (!configuration.containsKey("connection_ttl")) {
                setConnectionTTL(-1, MILLIS);
            }

            if (!configuration.containsKey("client_retry_on_failures")) {
                retryOnFailures(ClientFaultCause.NoHttpResponse, ClientFaultCause.ConnectTimeout, ClientFaultCause.ConnectionRequestTimeout);
            }

            if (!configuration.containsKey("client_network_buffer_size")) {
                setClientNetworkBufferSize(DEFAULT_NETWORK_BUFFER_SIZE);
            }

            if (!configuration.containsKey(ClickHouseClientOption.RETRY.getKey())) {
                setMaxRetries(3);
            }
        }
    }

    private ClickHouseNode getServerNode() {
        // TODO: implement load balancing using existing logic
        return this.serverNodes.get(0);
    }

    /**
     * Pings the server to check if it is alive
     * @return true if the server is alive, false otherwise
     */
    public boolean ping() {
        return ping(getOperationTimeout());
    }

    /**
     * Pings the server to check if it is alive. Maximum timeout is 10 minutes.
     *
     * @param timeout timeout in milliseconds
     * @return true if the server is alive, false otherwise
     */
    public boolean ping(long timeout) {
        if (useNewImplementation) {
            try (QueryResponse response = query("SELECT 1 FORMAT TabSeparated").get(timeout, TimeUnit.MILLISECONDS)) {
                return true;
            } catch (Exception e) {
                return false;
            }
        } else {
            return oldClient.ping(getServerNode(), Math.toIntExact(timeout));
        }
    }

    /**
     * 
Registers a POJO class and maps its fields to a table schema
     *
     * @param clazz - class of a POJO
     * @param schema - correlating table schema
     */
    public void register(Class clazz, TableSchema schema) {
        LOG.debug("Registering POJO: {}", clazz.getName());

        //Create a new POJOSerializer with static .serialize(object, columns) methods
        List serializers = new ArrayList<>();
        Map getterMethods = new HashMap<>();

        for (Method method: clazz.getMethods()) {//Clean up the method names
            String methodName = method.getName();
            if (methodName.startsWith("get") || methodName.startsWith("has")) {
                methodName = methodName.substring(3).toLowerCase();
                getterMethods.put(methodName, method);
            } if (methodName.startsWith("is")) {
                methodName = methodName.substring(2).toLowerCase();
                getterMethods.put(methodName, method);
            }
        }
        this.getterMethods.put(clazz, getterMethods);//Store the getter methods for later use

        for (ClickHouseColumn column : schema.getColumns()) {
            String columnName = column.getColumnName().toLowerCase().replace("_", "").replace(".","");
            serializers.add((obj, stream) -> {
                if (!getterMethods.containsKey(columnName)) {
                    LOG.warn("No getter method found for column: {}", columnName);
                    return;
                }
                Method getterMethod = this.getterMethods.get(clazz).get(columnName);
                Object value = getterMethod.invoke(obj);
                boolean hasDefaults = this.hasDefaults.get(clazz);

                //Handle null values
                if (value == null) {
                    if (hasDefaults && !column.hasDefault()) {//Send this only if there is no default
                        BinaryStreamUtils.writeNonNull(stream);
                    }
                    BinaryStreamUtils.writeNull(stream);//We send this regardless of default or nullable
                    return;
                }

                //Handle default
                if (hasDefaults) {
                    BinaryStreamUtils.writeNonNull(stream);//Write 0
                }

                //Handle nullable
                if (column.isNullable()) {
                    BinaryStreamUtils.writeNonNull(stream);//Write 0
                }

                //Handle the different types
                SerializerUtils.serializeData(stream, value, column);
            });
        }
        this.serializers.put(clazz, serializers);
        this.hasDefaults.put(clazz, schema.hasDefaults());
    }

    /**
     * 
Sends write request to database. List of objects is converted into a most suitable format
     * then it is sent to a server. Members of the list must be pre-registered using
     * {@link #register(Class, TableSchema)} method:
     *
     * 
{@code
     * client.register(SamplePOJO.class, tableSchema);
     * List