/** @return number of bytes per term, based on the NumericValue.requiredBits() */
@Override
public long bytesPerValue(BytesRef term) {
// Estimate about about 0.8 (8 / 10) compression ratio for
// numbers, but at least 4 bytes
return Math.max(type.requiredBits() / 10, 4);
}
protected CommonSettings.MemoryStorageFormat chooseStorageFormat(
LeafReader reader,
PackedLongValues values,
Ordinals build,
RandomAccessOrds ordinals,
long minValue,
long maxValue,
float acceptableOverheadRatio,
int pageSize) {
CommonSettings.MemoryStorageFormat format;
// estimate memory usage for a single packed array
long packedDelta = maxValue - minValue + 1; // allow for a missing value
// valuesDelta can be negative if the difference between max and min values overflows the
// positive side of longs.
int bitsRequired = packedDelta < 0 ? 64 : PackedInts.bitsRequired(packedDelta);
PackedInts.FormatAndBits formatAndBits =
PackedInts.fastestFormatAndBits(reader.maxDoc(), bitsRequired, acceptableOverheadRatio);
final long singleValuesSize =
formatAndBits.format.longCount(
PackedInts.VERSION_CURRENT, reader.maxDoc(), formatAndBits.bitsPerValue)
* 8L;
// ordinal memory usage
final long ordinalsSize = build.ramBytesUsed() + values.ramBytesUsed();
// estimate the memory signature of paged packing
long pagedSingleValuesSize =
(reader.maxDoc() / pageSize + 1) * RamUsageEstimator.NUM_BYTES_OBJECT_REF; // array of pages
int pageIndex = 0;
long pageMinOrdinal = Long.MAX_VALUE;
long pageMaxOrdinal = Long.MIN_VALUE;
for (int i = 1; i < reader.maxDoc(); ++i, pageIndex = (pageIndex + 1) % pageSize) {
ordinals.setDocument(i);
if (ordinals.cardinality() > 0) {
long ordinal = ordinals.ordAt(0);
pageMaxOrdinal = Math.max(ordinal, pageMaxOrdinal);
pageMinOrdinal = Math.min(ordinal, pageMinOrdinal);
}
if (pageIndex == pageSize - 1) {
// end of page, we now know enough to estimate memory usage
pagedSingleValuesSize +=
getPageMemoryUsage(
values, acceptableOverheadRatio, pageSize, pageMinOrdinal, pageMaxOrdinal);
pageMinOrdinal = Long.MAX_VALUE;
pageMaxOrdinal = Long.MIN_VALUE;
}
}
if (pageIndex > 0) {
// last page estimation
pageIndex++;
pagedSingleValuesSize +=
getPageMemoryUsage(
values, acceptableOverheadRatio, pageSize, pageMinOrdinal, pageMaxOrdinal);
}
if (ordinalsSize < singleValuesSize) {
if (ordinalsSize < pagedSingleValuesSize) {
format = CommonSettings.MemoryStorageFormat.ORDINALS;
} else {
format = CommonSettings.MemoryStorageFormat.PAGED;
}
} else {
if (pagedSingleValuesSize < singleValuesSize) {
format = CommonSettings.MemoryStorageFormat.PAGED;
} else {
format = CommonSettings.MemoryStorageFormat.PACKED;
}
}
return format;
}