Align max dml-batch-size with the implementation (#1575)

Author: yktakaha4

doc/command-line-flags.md

@@ -119,7 +119,7 @@ See also: [`skip-foreign-key-checks`](#skip-foreign-key-checks)
 
 `gh-ost` reads event from the binary log and applies them onto the _ghost_ table. It does so in batched writes: grouping multiple events to apply in a single transaction. This gives better write throughput as we don't need to sync the transaction log to disk for each event.
 
-The `--dml-batch-size` flag controls the size of the batched write. Allowed values are `1 - 100`, where `1` means no batching (every event from the binary log is applied onto the _ghost_ table on its own transaction). Default value is `10`.
+The `--dml-batch-size` flag controls the size of the batched write. Allowed values are `1 - 1000`, where `1` means no batching (every event from the binary log is applied onto the _ghost_ table on its own transaction). Default value is `10`.
 
 Why is this behavior configurable? Different workloads have different characteristics. Some workloads have very large writes, such that aggregating even `50` writes into a transaction makes for a significant transaction size. On other workloads write rate is high such that one just can't allow for a hundred more syncs to disk per second. The default value of `10` is a modest compromise that should probably work very well for most workloads. Your mileage may vary.
 

go/cmd/gh-ost/main.go

@@ -106,7 +106,7 @@ func main() {
 	flag.BoolVar(&migrationContext.CutOverExponentialBackoff, "cut-over-exponential-backoff", false, "Wait exponentially longer intervals between failed cut-over attempts. Wait intervals obey a maximum configurable with 'exponential-backoff-max-interval').")
 	exponentialBackoffMaxInterval := flag.Int64("exponential-backoff-max-interval", 64, "Maximum number of seconds to wait between attempts when performing various operations with exponential backoff.")
 	chunkSize := flag.Int64("chunk-size", 1000, "amount of rows to handle in each iteration (allowed range: 10-100,000)")
-	dmlBatchSize := flag.Int64("dml-batch-size", 10, "batch size for DML events to apply in a single transaction (range 1-100)")
+	dmlBatchSize := flag.Int64("dml-batch-size", 10, "batch size for DML events to apply in a single transaction (range 1-1000)")
 	defaultRetries := flag.Int64("default-retries", 60, "Default number of retries for various operations before panicking")
 	flag.BoolVar(&migrationContext.PanicOnWarnings, "panic-on-warnings", false, "Panic when SQL warnings are encountered when copying a batch indicating data loss")
 	cutOverLockTimeoutSeconds := flag.Int64("cut-over-lock-timeout-seconds", 3, "Max number of seconds to hold locks on tables while attempting to cut-over (retry attempted when lock exceeds timeout) or attempting instant DDL")