add CLICKHOUSE_MAX_CONNECTIONS config parameter to allow parallel e…

…xecution `FREEZE` / `UNFREEZE`

ChangeLog.md

@@ -1,6 +1,7 @@
 # v2.4.20
 IMPROVEMENTS
 - refactoring of `create` command to allow parallel execution of `FREEZE` and `UNFREEZE` and table level parallelization `object_disk.CopyObject`
+- add `CLICKHOUSE_MAX_CONNECTIONS` config parameter to allow parallel execution `FREEZE` / `UNFREEZE`
 
 # v2.4.19
 BUG FIXES

ReadMe.md

@@ -463,6 +463,7 @@ clickhouse:
   backup_mutations: true # CLICKHOUSE_BACKUP_MUTATIONS, allow backup mutations from system.mutations WHERE is_done AND apply it during restore
   restore_as_attach: false # CLICKHOUSE_RESTORE_AS_ATTACH, allow restore tables which have inconsistent data parts structure and mutations in progress
   check_parts_columns: true # CLICKHOUSE_CHECK_PARTS_COLUMNS, check data types from system.parts_columns during create backup to guarantee mutation is complete
+  max_connections: 0 # CLICKHOUSE_MAX_CONNECTIONS, how many parallel connections could be opened during operations
 azblob:
   endpoint_suffix: "core.windows.net" # AZBLOB_ENDPOINT_SUFFIX
   account_name: ""             # AZBLOB_ACCOUNT_NAME

pkg/clickhouse/clickhouse.go

@@ -60,8 +60,8 @@ func (ch *ClickHouse) Connect() error {
 			"receive_timeout": int(timeout.Seconds()),
 			"send_timeout":    int(timeout.Seconds()),
 		},
-		MaxOpenConns:    1,
-		ConnMaxLifetime: 0,
+		MaxOpenConns:    ch.Config.MaxConnections,
+		ConnMaxLifetime: timeout,
 		MaxIdleConns:    0,
 		DialTimeout:     timeout,
 		ReadTimeout:     timeout,

pkg/config/config.go

@@ -220,6 +220,7 @@ type ClickHouseConfig struct {
 	TLSKey                           string            `yaml:"tls_key" envconfig:"CLICKHOUSE_TLS_KEY"`
 	TLSCert                          string            `yaml:"tls_cert" envconfig:"CLICKHOUSE_TLS_CERT"`
 	TLSCa                            string            `yaml:"tls_ca" envconfig:"CLICKHOUSE_TLS_CA"`
+	MaxConnections                   int               `yaml:"max_connections" envconfig:"CLICKHOUSE_MAX_CONNECTIONS"`
 	Debug                            bool              `yaml:"debug" envconfig:"CLICKHOUSE_DEBUG"`
 }