var parquetSupport bool

func init() {
	parquetSupport = env.Get("MINIO_API_SELECT_PARQUET", config.EnableOff) == config.EnableOn
}

var bufPool = sync.Pool{
	New: func() interface{} {
		// make a buffer with a reasonable capacity.
		return bytes.NewBuffer(make([]byte, 0, maxRecordSize))
	},
}

var bufioWriterPool = sync.Pool{
	New: func() interface{} {
		// io.Discard is just used to create the writer. Actual destination

	dst = append(dst, in...)
	return dst, err
}

// csvSplitSize is the size of each block.
// Blocks will read this much and find the first following newline.
// 128KB appears to be a very reasonable default.
const csvSplitSize = 128 << 10

// startReaders will read the header if needed and spin up a parser
// and a number of workers based on GOMAXPROCS.

//
// First, we read the chunk size but fail if it is larger
// than 16 MiB. We must not accept arbitrary large chunks.
// One 16 MiB is a reasonable max limit.
//
// Then we read the signature and payload data. We compute the SHA256 checksum
// of the payload and verify that it matches the expected signature value.
//

// is more efficient than decrypting ETags sequentually.
func DecryptETags(ctx context.Context, k kms.KMS, objects []ObjectInfo) error {
	const BatchSize = 250 // We process the objects in batches - 250 is a reasonable default.
	var (
		metadata = make([]map[string]string, 0, BatchSize)
		buckets  = make([]string, 0, BatchSize)
		names    = make([]string, 0, BatchSize)
	)
	for len(objects) > 0 {
		N := BatchSize

			pbzip2.BZConcurrency((runtime.GOMAXPROCS(0)+1)/2),
			pbzip2.BZConcurrencyPool(bz2Limiter),
		))
		pr.closer = &nopReadCloser{fn: cancel}
	case zstdType:
		// Set a max window of 64MB. More than reasonable.
		zr, err := zstd.NewReader(scannedReader, zstd.WithDecoderConcurrency(2), zstd.WithDecoderMaxWindow(64<<20))
		if err != nil {
			return nil, errInvalidCompression(err, compType)
		}
		r = zr

	dst = append(dst, in...)
	return dst, err
}

// jsonSplitSize is the size of each block.
// Blocks will read this much and find the first following newline.
// 128KB appears to be a very reasonable default.
const jsonSplitSize = 128 << 10

// startReaders will read the header if needed and spin up a parser
// and a number of workers based on GOMAXPROCS.

// compacted until the limit is reached.
//
// This ensures that any branch will never contain an unreasonable amount of other branches,
// and also that small branches with few objects don't take up unreasonable amounts of space.
// This keeps the cache size at a reasonable size for all buckets.
//
// Whenever a branch is scanned, it is assumed that it will be un-compacted