The informations of LRU in trace file are inconsistent!

Question

I dump the buffers and want to check the information of LRU list.
alter system set events 'immediate trace name buffers level 4';
then , I find the information below in the trace file:
CHAIN: 4331 LOC: c0000000164484c0 HEAD: [c000000015febee8,c000000015febee8]
BH (c000000015febee8) file#: 4 rdba: 0x01000430 (4/1072) class: 1 ba: c000000015dcc000
set: 12 blksize: 8192 bsi: 0 set-flg: 2 pwbcnt: 0
dbwrid: 1 obj: 19576 objn: 19486 tsn: 4 afn: 4
hash: [c0000000164484c0,c0000000164484c0] lru: [c000000015fec060,c000000015febe70]
lru-flags:
ckptq: [NULL] fileq: [NULL] objq: [c0000000d4c3ee78,c000000015fec1c0]
st: XCURRENT md: NULL tch: 4
flags: only_sequential_access
LRBA: [0x0.0.0] HSCN: [0xffff.ffffffff] HSUB: [65535]
buffer tsn: 4 rdba: 0x01000430 (4/1072)
scn: 0x0000.0054cfb3 seq: 0x01 flg: 0x04 tail: 0xcfb30601
frmt: 0x02 chkval: 0x511e type: 0x06=trans data
Hex dump of block: st=0, typ_found=1
Please watch:
*lru: [c000000015fec060,c000000015febe70]*
that means the next_lru buffer is : c000000015fec060 and the previous_lru buffer is c000000015febe70.
However, I find the lru list in the same trace file :
MAIN RPL_LST Queue header (NEXT_DIRECTION)[c000000015fe96b8,c0000000163fbb48]
c000000015febcf8=>c000000015febdf0=>c000000015febee8=>c000000015febfe0=>c000000015fec0d8=>c000000015fec1d0
c000000015fec2c8=>c000000015fec3c0=>c000000015fec4b8=>c000000015fec5b0=>c000000015fec6a8=>c000000015fec7a0=>
Please watch carefully:
c000000015febdf0=>c000000015febee8=>c000000015febfe0=>
that means the  next_lru buffer is : c000000015febfe0 and the previous_lru buffer is c000000015febdf0.
1:Which one is correct and why these 2 informations are inconsistent?

Answer 1

Hi Sowmya,
when you refer to my Excel Export tutorial on SDN: <a href="https://wiki.sdn.sap.com/wiki/x/0mQ">Exporting Table Data Using On-Demand Streams - SAP NetWeaver 7.0</a>:
use <b>LinkedHashMap</b> instead of <i>HashMap</i>:
  private Map getProductColumnInfos() {
    Map columnInfosMap = new LinkedHashMap();
    columnInfosMap.put(IPrivateTableCompBasketView.IProductsElement.QUANTITY, "Quantity");
    columnInfosMap.put(IPrivateTableCompBasketView.IProductsElement.ARTICLE, "Article");
    columnInfosMap.put(IPrivateTableCompBasketView.IProductsElement.COLOR, "Color");
    columnInfosMap.put(IPrivateTableCompBasketView.IProductsElement.PRICE, "Price in EURO");
    columnInfosMap.put(
      IPrivateTableCompBasketView.IProductsElement.TOTAL__PER__ARTICLE,
      "Total Per Article In Euro");
    return columnInfosMap;
This keeps the order of key-displaytext-pairs passed by the client (table component) to the service (excel export component) stable.
Regards, Bertram