Let $X$ be a projective variety with only normal crossing singularity. Is there a description of the derived category or the category of perfect complexes? What about the existence of semiorthogonal decomposition?


Please provide a reference if this kind of study exists in the literature..



Derived category of singular varieties
Let $\tilde{X}\_k$ be the normalization of the closed $k$-codimension stratum, so $\tilde{X}\_0$ is the normalization of $X$. Then there is a diagram of pullback functors between the categories $\text{Perf}(\tilde{X}\_k),$ such that $\text{Perf}(X)$ is the pullback of this diagram in the $\infty$-category of derived categories (for example perfect derived sheaves on the cross $xy = 0$ are pairs of sheaves on $\mathbb{A}^1$ with fiber at $0$ identified). You can then perhaps use this paper <https://arxiv.org/pdf/1901.01257.pdf> by Scherotzke-Sibilla-Talpo to glue semiorthogonal decompositions on the $\text{Perf}(\tilde{X}\_i)$ to a semiorthogonal decomposition on $X$. 


Of course if you're just interested in some (unbounded) quasicoherent derived category, like for example $D^-\text{QCoh}$ then the filtration itself gives a semiorthogonal decomposition (define the filtered piece $D^-\text{QCoh}\_{\le k}$ to be the category of sheaves supported on the closed $k$-stratum. Then the semi-orthogonal pieces associated to this filtration will be categories $D^-\text{QCoh}\_k$ generated by pushforwards of sheaves from the *open* $k$-dimensional stratum).


