MergeCol.java

package org.opencloudb.mpp;

public class MergeCol {
	public static final int MERGE_COUNT = 1;
	public static final int MERGE_SUM = 2;
	public static final int MERGE_MIN = 3;
	public static final int MERGE_MAX = 4;
	public static final int MERGE_UNSUPPORT = -1;
	public static final int MERGE_NOMERGE = -2;
	public final int mergeType;
	public final ColMeta colMeta;

	public MergeCol(ColMeta colMeta, int mergeType) {
		super();
		this.colMeta = colMeta;
		this.mergeType = mergeType;
	}

	public static int getMergeType(String mergeType) {
		if ("COUNT".equalsIgnoreCase(mergeType)) {
			return MERGE_COUNT;
		} else if ("SUM".equalsIgnoreCase(mergeType)) {
			return MERGE_SUM;
		} else if ("MIN".equalsIgnoreCase(mergeType)) {
			return MERGE_MIN;
		} else if ("MAX".equalsIgnoreCase(mergeType)) {
			return MERGE_MAX;
		} else {
			return MERGE_UNSUPPORT;
		}
	}

	public static int tryParseAggCol(String column) {
		// MIN(*),MAX(*),COUNT(*),SUM
		if (column.length() < 5) {
			return -1;
		}
		column = column.toUpperCase();

		if (column.startsWith("COUNT(")) {
			return MERGE_COUNT;
		} else if (column.startsWith("SUM(")) {
			return MERGE_SUM;
		} else if (column.startsWith("MIN(")) {
			return MERGE_MIN;
		} else if (column.startsWith("MAX(")) {
			return MERGE_MAX;
		} else if (column.startsWith("AVG(")) {
			return MERGE_UNSUPPORT;
		} else {
			return MERGE_NOMERGE;
		}
	}
}