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keisku / gorilla

An effective time-series data compression/decompression method based on Facebook's Gorilla.

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compression does not work well

CodingCrush opened this issue · comments

commented 
func Test_gorilla(t *testing.T) {
	var buf bytes.Buffer
	c, finish, err := gorilla.NewCompressor(&buf, 27550378*60)
	assert.NoError(t, err)

	for i := 27550378; i < 27550388; i++ {
		t.Log("write: ", uint32(i*60), float64(i))
		assert.NoError(t, c.Compress(uint32(i*60), float64(i)))
	}
	assert.NoError(t, finish())

	d, _, err := gorilla.NewDecompressor(bytes.NewReader(buf.Bytes()))
	assert.NoError(t, err)

	itr := d.Iterator()
	for itr.Next() {
		fmt.Println(itr.At())
	}
}

the output is

1653022680 2.7550378e+07
1653022740 3.190115827897793e+84
1653022800 2.054801063973621e-147
1653022860 2.3792970816456578e-70
1653022920 1.5325406469947978e-301
1653022980 1.7745608335663593e-224
1653023040 1.774561542092724e-224
1653023100 1.7745614776812363e-224
1653023160 1.7745616709156994e-224
1653023220 1.7745616065042117e-224
commented

fix function compressValue

	leadingZeros := uint8(bits.LeadingZeros64(xor))
	trailingZeros := uint8(bits.TrailingZeros64(xor))

	if leadingZeros >= 32 {
		leadingZeros = 31
	}
        if c.leadingZeros != ^uint8(0) && c.leadingZeros <= leadingZeros && c.trailingZeros <= trailingZeros {
                // do something
        }
commented