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https://issues.apache.org/jira/browse/PHOENIX-1875?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14527733#comment-14527733
]
ASF GitHub Bot commented on PHOENIX-1875:
-----------------------------------------
Github user dumindux commented on a diff in the pull request:
https://github.com/apache/phoenix/pull/79#discussion_r29639284
--- Diff:
phoenix-core/src/main/java/org/apache/phoenix/schema/types/PArrayDataType.java
---
@@ -543,6 +544,151 @@ private static void writeEndBytes(byte[] array, int
newOffsetArrayPosition, int
Bytes.putByte(array, newOffsetArrayPosition + offsetArrayLength +
byteSize + 2 * Bytes.SIZEOF_INT, header);
}
+ public static boolean prependItemToArray(ImmutableBytesWritable ptr,
int length, int offset, byte[] arrayBytes, PDataType baseType, int arrayLength,
Integer maxLength, SortOrder sortOrder) {
+ int elementLength = maxLength == null ? ptr.getLength() :
maxLength;
+ if (ptr.getLength() == 0) {
+ elementLength = 0;
+ }
+ //padding
+ if (elementLength > ptr.getLength()) {
+ baseType.pad(ptr, elementLength, sortOrder);
+ }
+ int elementOffset = ptr.getOffset();
+ byte[] elementBytes = ptr.get();
+
+ byte[] newArray;
+ if (!baseType.isFixedWidth()) {
+ int offsetArrayPosition = Bytes.toInt(arrayBytes, offset +
length - Bytes.SIZEOF_INT - Bytes.SIZEOF_INT - Bytes.SIZEOF_BYTE,
Bytes.SIZEOF_INT);
+ int offsetArrayLength = length - offsetArrayPosition -
Bytes.SIZEOF_INT - Bytes.SIZEOF_INT - Bytes.SIZEOF_BYTE;
+ arrayLength = Math.abs(arrayLength);
+
+ //checks whether offset array consists of shorts or integers
+ boolean useInt = offsetArrayLength / arrayLength ==
Bytes.SIZEOF_INT;
+ boolean convertToInt = false;
+ int endElementPosition = getOffset(arrayBytes, arrayLength -
1, !useInt, offsetArrayPosition + offset) + elementLength + Bytes.SIZEOF_BYTE;
+ int newOffsetArrayPosition;
+ int offsetShift;
+ int firstNonNullElementPosition = 0;
+ int currentPosition = 0;
+ //handle the case where prepended element is null
+ if (elementLength == 0) {
+ int nulls = 1;
+ //counts the number of nulls which are already at the
beginning of the array
+ for (int index = 0; index < arrayLength; index++) {
+ int currOffset = getOffset(arrayBytes, index, !useInt,
offsetArrayPosition + offset);
+ if (arrayBytes[offset + currOffset] ==
QueryConstants.SEPARATOR_BYTE) {
+ nulls++;
+ } else {
+ //gets the offset of the first element after nulls
at the beginning
+ firstNonNullElementPosition = currOffset;
--- End diff --
firstNonNullElementPosition is used to know how many bytes are there before
the first non null element in the original array bytes(that is number of bytes
used to represent nulls at the beginning). when calculating the new array bytes
length, bytes required for storing nulls at the beginning is
calculated(nMultiplesOver255 + bytesForRemainingNulls + Bytes.SIZEOF_BYTE) and
added to the original array bytes length(length with all the bytes) then
firstNonNullElementPosition is subtracted from it to subtract the number of
bytes used to represent nulls at the beginning in the original array(since
those are included in the original array bytes length)
> implement ARRAY_PREPEND built in function
> -----------------------------------------
>
> Key: PHOENIX-1875
> URL: https://issues.apache.org/jira/browse/PHOENIX-1875
> Project: Phoenix
> Issue Type: Sub-task
> Reporter: Dumindu Buddhika
> Assignee: Dumindu Buddhika
> Attachments: PHOENIX-1875-v2.patch
>
>
> ARRAY_PREPEND(1, ARRAY[2, 3]) = ARRAY[1, 2, 3]
> ARRAY_PREPEND("a", ARRAY["b", "c"]) = ARRAY["a", "b", "c"]
> ARRAY_PREPEND(null, ARRAY["b", "c"]) = ARRAY[null, "b", "c"]
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