我需要同时从两个不同的 DbContext 访问数据，确保每个都使用 READ UNCOMMITTED 进行查询（实际上，重要的是它不会锁定它迭代的行 - 将 WITH NO LOCK 添加到查询中也工作）。
你如何使用实体框架来做到这一点？如果我将两个查询中的每一个都包装在 TransactionScope 中，它会尝试将事务提升到 MSDTC，这对我们来说不是一个选项。
private static IEnumerable<Image> EnumerateSourceImages()
{
using (var dbContext = new SourceDbContext())
{
using (var transScope = new TransactionScope(
TransactionScopeOption.RequiresNew,
new TransactionOptions() {
IsolationLevel = IsolationLevel.ReadUncommitted
}
)
)
{
var imagesSourceQuery = dbContext.ImageDatas
.AsNoTracking()
.OrderBy(imageData => imageData.ImageID)
foreach (var image in imagesSourceQuery)
{
yield return image;
}
transScope.Complete();
}
}
}
private static IEnumerable<Image> EnumerateDestinationImages()
{
using (var dbContext = new DestinationDbContext())
{
using (var transScope = new TransactionScope(
TransactionScopeOption.RequiresNew,
new TransactionOptions() {
IsolationLevel = IsolationLevel.ReadUncommitted
}
)
)
{
var imagesSourceQuery = dbContext.ImageDatas
.AsNoTracking()
.OrderBy(imageData => imageData.ImageID)
foreach (var image in imagesSourceQuery)
{
yield return image;
}
transScope.Complete();
}
}
}
private static void main(string[] args){
{
IEnumerator<ItemImage> sourceImagesEnumerator = null;
IEnumerator<ItemImage> destImagesEnumerator = null;
try{
sourceImagesEnumerator = EnumerateSourceImages().GetEnumerator();
destImagesEnumerator = EnumerateDestinationImages().GetEnumerator();
bool sourceHasMore = sourceImagesEnumerator.MoveNext();
//Exception on next line about MSDTC Promotion
bool destHasMore = destImagesEnumerator.MoveNext();
} finally{
if(sourceImagesEnumerator != null) sourceImagesEnumerator.Dispose();
if(destImagesEnumerator != null) destImagesEnumerator.Dispose():
}
}